Eduard Zingerman [Sat, 1 Mar 2025 00:01:47 +0000 (16:01 -0800)]
veristat: Report program type guess results to sdterr
In order not to pollute CSV output, e.g.:
$ ./veristat -o csv exceptions_ext.bpf.o > test.csv
Using guessed program type 'sched_cls' for exceptions_ext.bpf.o/extension...
Using guessed program type 'sched_cls' for exceptions_ext.bpf.o/throwing_extension...
Peilin Ye [Mon, 3 Mar 2025 05:37:25 +0000 (05:37 +0000)]
bpf: Factor out check_load_mem() and check_store_reg()
Extract BPF_LDX and most non-ATOMIC BPF_STX instruction handling logic
in do_check() into helper functions to be used later. While we are
here, make that comment about "reserved fields" more specific.
Peilin Ye [Mon, 3 Mar 2025 05:37:19 +0000 (05:37 +0000)]
bpf: Factor out check_atomic_rmw()
Currently, check_atomic() only handles atomic read-modify-write (RMW)
instructions. Since we are planning to introduce other types of atomic
instructions (i.e., atomic load/store), extract the existing RMW
handling logic into its own function named check_atomic_rmw().
Remove the @insn_idx parameter as it is not really necessary. Use
'env->insn_idx' instead, as in other places in verifier.c.
Eric Dumazet [Sat, 1 Mar 2025 19:13:15 +0000 (19:13 +0000)]
bpf: no longer acquire map_idr_lock in bpf_map_inc_not_zero()
bpf_sk_storage_clone() is the only caller of bpf_map_inc_not_zero()
and is holding rcu_read_lock().
map_idr_lock does not add any protection, just remove the cost
for passive TCP flows.
Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Kui-Feng Lee <kuifeng@meta.com> Cc: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Link: https://lore.kernel.org/r/20250301191315.1532629-1-edumazet@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
====================
Global subprogs in RCU/{preempt,irq}-disabled sections
Small change to allow non-sleepable global subprogs in
RCU, preempt-disabled, and irq-disabled sections. For
now, we don't lift the limitation for locks as it requires
more analysis, and will do this one resilient spin locks
land.
This surfaced a bug where sleepable global subprogs were
allowed in RCU read sections, that has been fixed. Tests
have been added to cover various cases.
* Rename subprog_info[i].sleepable to might_sleep, which more
accurately reflects the nature of the bit. 'sleepable' means whether
a given context is allowed to, while might_sleep captures if it
does.
* Disallow extensions that might sleep to attach to targets that don't
sleep, since they'd be permitted to be called in atomic contexts. (Eduard)
* Add tests for mixing non-sleepable and sleepable global function
calls, and extensions attaching to non-sleepable global functions. (Eduard)
* Rename changes_pkt_data -> summarization
====================
selftests/bpf: Add tests for extending sleepable global subprogs
Add tests for freplace behavior with the combination of sleepable
and non-sleepable global subprogs. The changes_pkt_data selftest
did all the hardwork, so simply rename it and include new support
for more summarization tests for might_sleep bit.
selftests/bpf: Test sleepable global subprogs in atomic contexts
Add tests for rejecting sleepable and accepting non-sleepable global
function calls in atomic contexts. For spin locks, we still reject
all global function calls. Once resilient spin locks land, we will
carefully lift in cases where we deem it safe.
Yonghong Song [Mon, 24 Feb 2025 23:01:16 +0000 (15:01 -0800)]
bpf: Allow pre-ordering for bpf cgroup progs
Currently for bpf progs in a cgroup hierarchy, the effective prog array
is computed from bottom cgroup to upper cgroups (post-ordering). For
example, the following cgroup hierarchy
root cgroup: p1, p2
subcgroup: p3, p4
have BPF_F_ALLOW_MULTI for both cgroup levels.
The effective cgroup array ordering looks like
p3 p4 p1 p2
and at run time, progs will execute based on that order.
But in some cases, it is desirable to have root prog executes earlier than
children progs (pre-ordering). For example,
- prog p1 intends to collect original pkt dest addresses.
- prog p3 will modify original pkt dest addresses to a proxy address for
security reason.
The end result is that prog p1 gets proxy address which is not what it
wants. Putting p1 to every child cgroup is not desirable either as it
will duplicate itself in many child cgroups. And this is exactly a use case
we are encountering in Meta.
To fix this issue, let us introduce a flag BPF_F_PREORDER. If the flag
is specified at attachment time, the prog has higher priority and the
ordering with that flag will be from top to bottom (pre-ordering).
For example, in the above example,
root cgroup: p1, p2
subcgroup: p3, p4
Let us say p2 and p4 are marked with BPF_F_PREORDER. The final
effective array ordering will be
p2 p4 p3 p1
The verifier currently does not permit global subprog calls when a lock
is held, preemption is disabled, or when IRQs are disabled. This is
because we don't know whether the global subprog calls sleepable
functions or not.
In case of locks, there's an additional reason: functions called by the
global subprog may hold additional locks etc. The verifier won't know
while verifying the global subprog whether it was called in context
where a spin lock is already held by the program.
Perform summarization of the sleepable nature of a global subprog just
like changes_pkt_data and then allow calls to global subprogs for
non-sleepable ones from atomic context.
While making this change, I noticed that RCU read sections had no
protection against sleepable global subprog calls, include it in the
checks and fix this while we're at it.
Care needs to be taken to not allow global subprog calls when regular
bpf_spin_lock is held. When resilient spin locks is held, we want to
potentially have this check relaxed, but not for now.
Also make sure extensions freplacing global functions cannot do so
in case the target is non-sleepable, but the extension is. The other
combination is ok.
Tests are included in the next patch to handle all special conditions.
====================
Optimize bpf selftest to increase CI success rate
1. Optimized some static bound port selftests to avoid port occupation
when running test_progs -j.
2. Optimized the retry logic for test_maps.
Some Failed CI:
https://github.com/kernel-patches/bpf/actions/runs/13275542359/job/37064974076
https://github.com/kernel-patches/bpf/actions/runs/13549227497/job/37868926343
https://github.com/kernel-patches/bpf/actions/runs/13548089029/job/37865812030
https://github.com/kernel-patches/bpf/actions/runs/13553536268/job/37883329296
(Perhaps it's due to the large number of pull requests requiring CI runs?)
====================
Jiayuan Chen [Thu, 27 Feb 2025 14:26:46 +0000 (22:26 +0800)]
selftests/bpf: Fixes for test_maps test
BPF CI has failed 3 times in the last 24 hours. Add retry for ENOMEM.
It's similar to the optimization plan:
commit 2f553b032cad ("selftsets/bpf: Retry map update for non-preallocated per-cpu map")
Introduce a new kfunc, bpf_dynptr_copy, which enables copying of
data from one dynptr to another. This functionality may be useful in
scenarios such as capturing XDP data to a ring buffer.
The patch set is split into 3 patches:
1. Refactor bpf_dynptr_read and bpf_dynptr_write by extracting code into
static functions, that allows calling them with no compiler warnings
2. Introduce bpf_dynptr_copy
3. Add tests for bpf_dynptr_copy
v2->v3:
* Implemented bpf_memcmp in dynptr_success.c test, as __builtin_memcmp
was not inlined on GCC-BPF.
====================
Mykyta Yatsenko [Wed, 26 Feb 2025 18:32:00 +0000 (18:32 +0000)]
bpf/helpers: Introduce bpf_dynptr_copy kfunc
Introducing bpf_dynptr_copy kfunc allowing copying data from one dynptr to
another. This functionality is useful in scenarios such as capturing XDP
data to a ring buffer.
The implementation consists of 4 branches:
* A fast branch for contiguous buffer capacity in both source and
destination dynptrs
* 3 branches utilizing __bpf_dynptr_read and __bpf_dynptr_write to copy
data to/from non-contiguous buffer
Mykyta Yatsenko [Wed, 26 Feb 2025 18:31:59 +0000 (18:31 +0000)]
bpf/helpers: Refactor bpf_dynptr_read and bpf_dynptr_write
Refactor bpf_dynptr_read and bpf_dynptr_write helpers: extract code
into the static functions namely __bpf_dynptr_read and
__bpf_dynptr_write, this allows calling these without compiler warnings.
====================
selftests/bpf: implement setting global variables in veristat
From: Mykyta Yatsenko <yatsenko@meta.com>
To better verify some complex BPF programs by veristat, it would be useful
to preset global variables. This patch set implements this functionality
and introduces tests for veristat.
v4->v5
* Rework parsing to use sscanf for integers
* Addressing nits
v3->v4:
* Fixing bug in set_global_var introduced by refactoring in previous patch set
* Addressed nits from Eduard
v2->v3:
* Reworked parsing of the presets, using sscanf to split into variable and
value, but still use strtoll/strtoull to support range checks when parsing
integers
* Fix test failures for no_alu32 & cpuv4 by checking if veristat binary is in
parent folder
* Introduce __CHECK_STR macro for simplifying checks in test
* Modify tests into sub-tests
====================
Mykyta Yatsenko [Tue, 25 Feb 2025 16:31:00 +0000 (16:31 +0000)]
selftests/bpf: Implement setting global variables in veristat
To better verify some complex BPF programs we'd like to preset global
variables.
This patch introduces CLI argument `--set-global-vars` or `-G` to
veristat, that allows presetting values to global variables defined
in BPF program. For example:
prog.c:
```
enum Enum { ELEMENT1 = 0, ELEMENT2 = 5 };
const volatile __s64 a = 5;
const volatile __u8 b = 5;
const volatile enum Enum c = ELEMENT2;
const volatile bool d = false;
char arr[4] = {0};
SEC("tp_btf/sched_switch")
int BPF_PROG(...)
{
bpf_printk("%c\n", arr[a]);
bpf_printk("%c\n", arr[b]);
bpf_printk("%c\n", arr[c]);
bpf_printk("%c\n", arr[d]);
return 0;
}
```
By default verification of the program fails:
```
./veristat prog.bpf.o
```
By presetting global variables, we can make verification pass:
```
./veristat wq.bpf.o -G "a = 0" -G "b = 1" -G "c = 2" -G "d = 3"
```
Alexei Starovoitov [Mon, 24 Feb 2025 22:16:37 +0000 (14:16 -0800)]
bpf: Fix deadlock between rcu_tasks_trace and event_mutex.
Fix the following deadlock:
CPU A
_free_event()
perf_kprobe_destroy()
mutex_lock(&event_mutex)
perf_trace_event_unreg()
synchronize_rcu_tasks_trace()
There are several paths where _free_event() grabs event_mutex
and calls sync_rcu_tasks_trace. Above is one such case.
CPU B
bpf_prog_test_run_syscall()
rcu_read_lock_trace()
bpf_prog_run_pin_on_cpu()
bpf_prog_load()
bpf_tracing_func_proto()
trace_set_clr_event()
mutex_lock(&event_mutex)
Delegate trace_set_clr_event() to workqueue to avoid
such lock dependency.
Yonghong Song [Thu, 7 Nov 2024 17:09:24 +0000 (09:09 -0800)]
docs/bpf: Document some special sdiv/smod operations
Patch [1] fixed possible kernel crash due to specific sdiv/smod operations
in bpf program. The following are related operations and the expected results
of those operations:
- LLONG_MIN/-1 = LLONG_MIN
- INT_MIN/-1 = INT_MIN
- LLONG_MIN%-1 = 0
- INT_MIN%-1 = 0
Those operations are replaced with codes which won't cause
kernel crash. This patch documents what operations may cause exception and
what replacement operations are.
Mahe Tardy [Tue, 25 Feb 2025 12:50:30 +0000 (12:50 +0000)]
bpf: add get_netns_cookie helper to cgroup_skb programs
This is needed in the context of Cilium and Tetragon to retrieve netns
cookie from hostns when traffic leaves Pod, so that we can correlate
skb->sk's netns cookie.
Amery Hung [Tue, 25 Feb 2025 23:35:45 +0000 (15:35 -0800)]
selftests/bpf: Test gen_pro/epilogue that generate kfuncs
Test gen_prologue and gen_epilogue that generate kfuncs that have not
been seen in the main program.
The main bpf program and return value checks are identical to
pro_epilogue.c introduced in commit 47e69431b57a ("selftests/bpf: Test
gen_prologue and gen_epilogue"). However, now when bpf_testmod_st_ops
detects a program name with prefix "test_kfunc_", it generates slightly
different prologue and epilogue: They still add 1000 to args->a in
prologue, add 10000 to args->a and set r0 to 2 * args->a in epilogue,
but involve kfuncs.
At high level, the alternative version of prologue and epilogue look
like this:
cgrp = bpf_cgroup_from_id(0);
if (cgrp)
bpf_cgroup_release(cgrp);
else
/* Perform what original bpf_testmod_st_ops prologue or
* epilogue does
*/
Since 0 is never a valid cgroup id, the original prologue or epilogue
logic will be performed. As a result, the __retval check should expect
the exact same return value.
Amery Hung [Tue, 25 Feb 2025 23:35:44 +0000 (15:35 -0800)]
bpf: Search and add kfuncs in struct_ops prologue and epilogue
Currently, add_kfunc_call() is only invoked once before the main
verification loop. Therefore, the verifier could not find the
bpf_kfunc_btf_tab of a new kfunc call which is not seen in user defined
struct_ops operators but introduced in gen_prologue or gen_epilogue
during do_misc_fixup(). Fix this by searching kfuncs in the patching
instruction buffer and add them to prog->aux->kfunc_tab.
Signed-off-by: Amery Hung <amery.hung@bytedance.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20250225233545.285481-1-ameryhung@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Nandakumar Edamana [Fri, 21 Feb 2025 21:01:11 +0000 (02:31 +0530)]
libbpf: Fix out-of-bound read
In `set_kcfg_value_str`, an untrusted string is accessed with the assumption
that it will be at least two characters long due to the presence of checks for
opening and closing quotes. But the check for the closing quote
(value[len - 1] != '"') misses the fact that it could be checking the opening
quote itself in case of an invalid input that consists of just the opening
quote.
This commit adds an explicit check to make sure the string is at least two
characters long.
Further investigation shows the reason is due to not 8-byte aligned
store of percpu pointer in htab_elem_set_ptr():
*(void __percpu **)(l->key + key_size) = pptr;
Note that the whole htab_elem alignment is 8 (for x86_64). If the key_size
is 4, that means pptr is stored in a location which is 4 byte aligned but
not 8 byte aligned. In mm/kmemleak.c, scan_block() scans the memory based
on 8 byte stride, so it won't detect above pptr, hence reporting the memory
leak.
So storing pptr with 8-byte alignment won't cause any problem and can fix
kmemleak too.
The issue can be reproduced with bpf selftest as well:
1. Enable CONFIG_DEBUG_KMEMLEAK config
2. Add a getchar() before skel destroy in test_hash_map() in prog_tests/for_each.c.
The purpose is to keep map available so kmemleak can be detected.
3. run './test_progs -t for_each/hash_map &' and a kmemleak should be reported.
Amery Hung [Fri, 21 Feb 2025 17:56:44 +0000 (09:56 -0800)]
bpf: Refactor check_ctx_access()
Reduce the variable passing madness surrounding check_ctx_access().
Currently, check_mem_access() passes many pointers to local variables to
check_ctx_access(). They are used to initialize "struct
bpf_insn_access_aux info" in check_ctx_access() and then passed to
is_valid_access(). Then, check_ctx_access() takes the data our from
info and write them back the pointers to pass them back. This can be
simpilified by moving info up to check_mem_access().
Amery Hung [Thu, 20 Feb 2025 22:15:31 +0000 (14:15 -0800)]
bpf: Do not allow tail call in strcut_ops program with __ref argument
Reject struct_ops programs with refcounted kptr arguments (arguments
tagged with __ref suffix) that tail call. Once a refcounted kptr is
passed to a struct_ops program from the kernel, it can be freed or
xchged into maps. As there is no guarantee a callee can get the same
valid refcounted kptr in the ctx, we cannot allow such usage.
Andrii Nakryiko [Thu, 20 Feb 2025 00:28:21 +0000 (16:28 -0800)]
libbpf: Fix hypothetical STT_SECTION extern NULL deref case
Fix theoretical NULL dereference in linker when resolving *extern*
STT_SECTION symbol against not-yet-existing ELF section. Not sure if
it's possible in practice for valid ELF object files (this would require
embedded assembly manipulations, at which point BTF will be missing),
but fix the s/dst_sym/dst_sec/ typo guarding this condition anyways.
Fixes: faf6ed321cf6 ("libbpf: Add BPF static linker APIs") Fixes: a46349227cd8 ("libbpf: Add linker extern resolution support for functions and global variables") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20250220002821.834400-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Hou Tao [Thu, 20 Feb 2025 04:22:59 +0000 (12:22 +0800)]
bpf: Use preempt_count() directly in bpf_send_signal_common()
bpf_send_signal_common() uses preemptible() to check whether or not the
current context is preemptible. If it is preemptible, it will use
irq_work to send the signal asynchronously instead of trying to hold a
spin-lock, because spin-lock is sleepable under PREEMPT_RT.
However, preemptible() depends on CONFIG_PREEMPT_COUNT. When
CONFIG_PREEMPT_COUNT is turned off (e.g., CONFIG_PREEMPT_VOLUNTARY=y),
!preemptible() will be evaluated as 1 and bpf_send_signal_common() will
use irq_work unconditionally.
Fix it by unfolding "!preemptible()" and using "preempt_count() != 0 ||
irqs_disabled()" instead.
Linus Torvalds [Thu, 20 Feb 2025 23:37:17 +0000 (15:37 -0800)]
Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Pull BPF fixes from Daniel Borkmann:
- Fix a soft-lockup in BPF arena_map_free on 64k page size kernels
(Alan Maguire)
- Fix a missing allocation failure check in BPF verifier's
acquire_lock_state (Kumar Kartikeya Dwivedi)
- Fix a NULL-pointer dereference in trace_kfree_skb by adding kfree_skb
to the raw_tp_null_args set (Kuniyuki Iwashima)
- Fix a deadlock when freeing BPF cgroup storage (Abel Wu)
- Fix a syzbot-reported deadlock when holding BPF map's freeze_mutex
(Andrii Nakryiko)
- Fix a use-after-free issue in bpf_test_init when eth_skb_pkt_type is
accessing skb data not containing an Ethernet header (Shigeru
Yoshida)
- Fix skipping non-existing keys in generic_map_lookup_batch (Yan Zhai)
- Several BPF sockmap fixes to address incorrect TCP copied_seq
calculations, which prevented correct data reads from recv(2) in user
space (Jiayuan Chen)
- Two fixes for BPF map lookup nullness elision (Daniel Xu)
- Fix a NULL-pointer dereference from vmlinux BTF lookup in
bpf_sk_storage_tracing_allowed (Jared Kangas)
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
selftests: bpf: test batch lookup on array of maps with holes
bpf: skip non exist keys in generic_map_lookup_batch
bpf: Handle allocation failure in acquire_lock_state
bpf: verifier: Disambiguate get_constant_map_key() errors
bpf: selftests: Test constant key extraction on irrelevant maps
bpf: verifier: Do not extract constant map keys for irrelevant maps
bpf: Fix softlockup in arena_map_free on 64k page kernel
net: Add rx_skb of kfree_skb to raw_tp_null_args[].
bpf: Fix deadlock when freeing cgroup storage
selftests/bpf: Add strparser test for bpf
selftests/bpf: Fix invalid flag of recv()
bpf: Disable non stream socket for strparser
bpf: Fix wrong copied_seq calculation
strparser: Add read_sock callback
bpf: avoid holding freeze_mutex during mmap operation
bpf: unify VM_WRITE vs VM_MAYWRITE use in BPF map mmaping logic
selftests/bpf: Adjust data size to have ETH_HLEN
bpf, test_run: Fix use-after-free issue in eth_skb_pkt_type()
bpf: Remove unnecessary BTF lookups in bpf_sk_storage_tracing_allowed
- tcp:
- adjust rcvq_space after updating scaling ratio
- drop secpath at the same time as we currently drop dst
- eth: gtp: suppress list corruption splat in gtp_net_exit_batch_rtnl().
Previous releases - always broken:
- vsock:
- fix variables initialization during resuming
- for connectible sockets allow only connected
- eth:
- geneve: fix use-after-free in geneve_find_dev()
- ibmvnic: don't reference skb after sending to VIOS"
* tag 'net-6.14-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (34 commits)
Revert "net: skb: introduce and use a single page frag cache"
net: allow small head cache usage with large MAX_SKB_FRAGS values
nfp: bpf: Add check for nfp_app_ctrl_msg_alloc()
tcp: drop secpath at the same time as we currently drop dst
net: axienet: Set mac_managed_pm
arp: switch to dev_getbyhwaddr() in arp_req_set_public()
net: Add non-RCU dev_getbyhwaddr() helper
sctp: Fix undefined behavior in left shift operation
selftests/bpf: Add a specific dst port matching
flow_dissector: Fix port range key handling in BPF conversion
selftests/net/forwarding: Add a test case for tc-flower of mixed port and port-range
flow_dissector: Fix handling of mixed port and port-range keys
geneve: Suppress list corruption splat in geneve_destroy_tunnels().
gtp: Suppress list corruption splat in gtp_net_exit_batch_rtnl().
dev: Use rtnl_net_dev_lock() in unregister_netdev().
net: Fix dev_net(dev) race in unregister_netdevice_notifier_dev_net().
net: Add net_passive_inc() and net_passive_dec().
net: pse-pd: pd692x0: Fix power limit retrieval
MAINTAINERS: trim the GVE entry
gve: set xdp redirect target only when it is available
...
Linus Torvalds [Thu, 20 Feb 2025 16:59:00 +0000 (08:59 -0800)]
Merge tag 'v6.14-rc3-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6
Pull smb client fixes from Steve French:
- Fix for chmod regression
- Two reparse point related fixes
- One minor cleanup (for GCC 14 compiles)
- Fix for SMB3.1.1 POSIX Extensions reporting incorrect file type
* tag 'v6.14-rc3-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
cifs: Treat unhandled directory name surrogate reparse points as mount directory nodes
cifs: Throw -EOPNOTSUPP error on unsupported reparse point type from parse_reparse_point()
smb311: failure to open files of length 1040 when mounting with SMB3.1.1 POSIX extensions
smb: client, common: Avoid multiple -Wflex-array-member-not-at-end warnings
smb: client: fix chmod(2) regression with ATTR_READONLY
Linus Torvalds [Thu, 20 Feb 2025 16:51:57 +0000 (08:51 -0800)]
Merge tag 'bcachefs-2025-02-20' of git://evilpiepirate.org/bcachefs
Pull bcachefs fixes from Kent Overstreet:
"Small stuff:
- The fsck code for Hongbo's directory i_size patch was wrong, caught
by transaction restart injection: we now have the CI running
another test variant with restart injection enabled
- Another fixup for reflink pointers to missing indirect extents:
previous fix was for fsck code, this fixes the normal runtime paths
- Another small srcu lock hold time fix, reported by jpsollie"
* tag 'bcachefs-2025-02-20' of git://evilpiepirate.org/bcachefs:
bcachefs: Fix srcu lock warning in btree_update_nodes_written()
bcachefs: Fix bch2_indirect_extent_missing_error()
bcachefs: Fix fsck directory i_size checking
Linus Torvalds [Thu, 20 Feb 2025 16:48:55 +0000 (08:48 -0800)]
Merge tag 'xfs-fixes-6.14-rc4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs fixes from Carlos Maiolino:
"Just a collection of bug fixes, nothing really stands out"
* tag 'xfs-fixes-6.14-rc4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: flush inodegc before swapon
xfs: rename xfs_iomap_swapfile_activate to xfs_vm_swap_activate
xfs: Do not allow norecovery mount with quotacheck
xfs: do not check NEEDSREPAIR if ro,norecovery mount.
xfs: fix data fork format filtering during inode repair
xfs: fix online repair probing when CONFIG_XFS_ONLINE_REPAIR=n
====================
net: remove the single page frag cache for good
This is another attempt at reverting commit dbae2b062824 ("net: skb:
introduce and use a single page frag cache"), as it causes regressions
in specific use-cases.
Reverting such commit uncovers an allocation issue for build with
CONFIG_MAX_SKB_FRAGS=45, as reported by Sabrina.
This series handle the latter in patch 1 and brings the revert in patch
2.
Note that there is a little chicken-egg problem, as I included into the
patch 1's changelog the splat that would be visible only applying first
the revert: I think current patch order is better for bisectability,
still the splat is useful for correct attribution.
====================
Paolo Abeni [Tue, 18 Feb 2025 18:29:40 +0000 (19:29 +0100)]
Revert "net: skb: introduce and use a single page frag cache"
After the previous commit is finally safe to revert commit dbae2b062824
("net: skb: introduce and use a single page frag cache"): do it here.
The intended goal of such change was to counter a performance regression
introduced by commit 3226b158e67c ("net: avoid 32 x truesize
under-estimation for tiny skbs").
Unfortunately, the blamed commit introduces another regression for the
virtio_net driver. Such a driver calls napi_alloc_skb() with a tiny
size, so that the whole head frag could fit a 512-byte block.
The single page frag cache uses a 1K fragment for such allocation, and
the additional overhead, under small UDP packets flood, makes the page
allocator a bottleneck.
Thanks to commit bf9f1baa279f ("net: add dedicated kmem_cache for
typical/small skb->head"), this revert does not re-introduce the
original regression. Actually, in the relevant test on top of this
revert, I measure a small but noticeable positive delta, just above
noise level.
The revert itself required some additional mangling due to recent updates
in the affected code.
Suggested-by: Eric Dumazet <edumazet@google.com> Fixes: dbae2b062824 ("net: skb: introduce and use a single page frag cache") Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
on kernel built with MAX_SKB_FRAGS=45, where SKB_WITH_OVERHEAD(1024)
is smaller than GRO_MAX_HEAD.
Such built additionally contains the revert of the single page frag cache
so that napi_get_frags() ends up using the page frag allocator, triggering
the splat.
Note that the underlying issue is independent from the mentioned
revert; address it ensuring that the small head cache will fit either TCP
and GRO allocation and updating napi_alloc_skb() and __netdev_alloc_skb()
to select kmalloc() usage for any allocation fitting such cache.
Reported-by: Sabrina Dubroca <sd@queasysnail.net> Suggested-by: Eric Dumazet <edumazet@google.com> Fixes: 3948b05950fd ("net: introduce a config option to tweak MAX_SKB_FRAGS") Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Sabrina Dubroca [Mon, 17 Feb 2025 10:23:35 +0000 (11:23 +0100)]
tcp: drop secpath at the same time as we currently drop dst
Xiumei reported hitting the WARN in xfrm6_tunnel_net_exit while
running tests that boil down to:
- create a pair of netns
- run a basic TCP test over ipcomp6
- delete the pair of netns
The xfrm_state found on spi_byaddr was not deleted at the time we
delete the netns, because we still have a reference on it. This
lingering reference comes from a secpath (which holds a ref on the
xfrm_state), which is still attached to an skb. This skb is not
leaked, it ends up on sk_receive_queue and then gets defer-free'd by
skb_attempt_defer_free.
The problem happens when we defer freeing an skb (push it on one CPU's
defer_list), and don't flush that list before the netns is deleted. In
that case, we still have a reference on the xfrm_state that we don't
expect at this point.
We already drop the skb's dst in the TCP receive path when it's no
longer needed, so let's also drop the secpath. At this point,
tcp_filter has already called into the LSM hooks that may require the
secpath, so it should not be needed anymore. However, in some of those
places, the MPTCP extension has just been attached to the skb, so we
cannot simply drop all extensions.
Nick Hu [Mon, 17 Feb 2025 05:58:42 +0000 (13:58 +0800)]
net: axienet: Set mac_managed_pm
The external PHY will undergo a soft reset twice during the resume process
when it wake up from suspend. The first reset occurs when the axienet
driver calls phylink_of_phy_connect(), and the second occurs when
mdio_bus_phy_resume() invokes phy_init_hw(). The second soft reset of the
external PHY does not reinitialize the internal PHY, which causes issues
with the internal PHY, resulting in the PHY link being down. To prevent
this, setting the mac_managed_pm flag skips the mdio_bus_phy_resume()
function.
Fixes: a129b41fe0a8 ("Revert "net: phy: dp83867: perform soft reset and retain established link"") Signed-off-by: Nick Hu <nick.hu@sifive.com> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://patch.msgid.link/20250217055843.19799-1-nick.hu@sifive.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
====================
net: core: improvements to device lookup by hardware address.
The first patch adds a new dev_getbyhwaddr() helper function for
finding devices by hardware address when the rtnl lock is held. This
prevents PROVE_LOCKING warnings that occurred when rtnl lock was held
but the RCU read lock wasn't. The common address comparison logic is
extracted into dev_comp_addr() to avoid code duplication.
The second coverts arp_req_set_public() to the new helper.
====================
Breno Leitao [Tue, 18 Feb 2025 13:49:31 +0000 (05:49 -0800)]
arp: switch to dev_getbyhwaddr() in arp_req_set_public()
The arp_req_set_public() function is called with the rtnl lock held,
which provides enough synchronization protection. This makes the RCU
variant of dev_getbyhwaddr() unnecessary. Switch to using the simpler
dev_getbyhwaddr() function since we already have the required rtnl
locking.
This change helps maintain consistency in the networking code by using
the appropriate helper function for the existing locking context.
Since we're not holding the RCU read lock in arp_req_set_public()
existing code could trigger false positive locking warnings.
Fixes: 941666c2e3e0 ("net: RCU conversion of dev_getbyhwaddr() and arp_ioctl()") Suggested-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: Breno Leitao <leitao@debian.org> Link: https://patch.msgid.link/20250218-arm_fix_selftest-v5-2-d3d6892db9e1@debian.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Breno Leitao [Tue, 18 Feb 2025 13:49:30 +0000 (05:49 -0800)]
net: Add non-RCU dev_getbyhwaddr() helper
Add dedicated helper for finding devices by hardware address when
holding rtnl_lock, similar to existing dev_getbyhwaddr_rcu(). This prevents
PROVE_LOCKING warnings when rtnl_lock is held but RCU read lock is not.
Extract common address comparison logic into dev_addr_cmp().
The context about this change could be found in the following
discussion:
Yu-Chun Lin [Tue, 18 Feb 2025 08:12:16 +0000 (16:12 +0800)]
sctp: Fix undefined behavior in left shift operation
According to the C11 standard (ISO/IEC 9899:2011, 6.5.7):
"If E1 has a signed type and E1 x 2^E2 is not representable in the result
type, the behavior is undefined."
Shifting 1 << 31 causes signed integer overflow, which leads to undefined
behavior.
Fix this by explicitly using '1U << 31' to ensure the shift operates on
an unsigned type, avoiding undefined behavior.
====================
flow_dissector: Fix handling of mixed port and port-range keys
This patchset contains two fixes for flow_dissector handling of mixed
port and port-range keys, for both tc-flower case and bpf case. Each
of them also comes with a selftest.
====================
Cong Wang [Tue, 18 Feb 2025 04:32:09 +0000 (20:32 -0800)]
flow_dissector: Fix port range key handling in BPF conversion
Fix how port range keys are handled in __skb_flow_bpf_to_target() by:
- Separating PORTS and PORTS_RANGE key handling
- Using correct key_ports_range structure for range keys
- Properly initializing both key types independently
This ensures port range information is correctly stored in its dedicated
structure rather than incorrectly using the regular ports key structure.
Fixes: 59fb9b62fb6c ("flow_dissector: Fix to use new variables for port ranges in bpf hook") Reported-by: Qiang Zhang <dtzq01@gmail.com> Closes: https://lore.kernel.org/netdev/CAPx+-5uvFxkhkz4=j_Xuwkezjn9U6kzKTD5jz4tZ9msSJ0fOJA@mail.gmail.com/ Cc: Yoshiki Komachi <komachi.yoshiki@gmail.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Jiri Pirko <jiri@resnulli.us> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Link: https://patch.msgid.link/20250218043210.732959-4-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cong Wang [Tue, 18 Feb 2025 04:32:08 +0000 (20:32 -0800)]
selftests/net/forwarding: Add a test case for tc-flower of mixed port and port-range
After this patch:
# ./tc_flower_port_range.sh
TEST: Port range matching - IPv4 UDP [ OK ]
TEST: Port range matching - IPv4 TCP [ OK ]
TEST: Port range matching - IPv6 UDP [ OK ]
TEST: Port range matching - IPv6 TCP [ OK ]
TEST: Port range matching - IPv4 UDP Drop [ OK ]
Cong Wang [Tue, 18 Feb 2025 04:32:07 +0000 (20:32 -0800)]
flow_dissector: Fix handling of mixed port and port-range keys
This patch fixes a bug in TC flower filter where rules combining a
specific destination port with a source port range weren't working
correctly.
The specific case was when users tried to configure rules like:
tc filter add dev ens38 ingress protocol ip flower ip_proto udp \
dst_port 5000 src_port 2000-3000 action drop
The root cause was in the flow dissector code. While both
FLOW_DISSECTOR_KEY_PORTS and FLOW_DISSECTOR_KEY_PORTS_RANGE flags
were being set correctly in the classifier, the __skb_flow_dissect_ports()
function was only populating one of them: whichever came first in
the enum check. This meant that when the code needed both a specific
port and a port range, one of them would be left as 0, causing the
filter to not match packets as expected.
Fix it by removing the either/or logic and instead checking and
populating both key types independently when they're in use.
Fixes: 8ffb055beae5 ("cls_flower: Fix the behavior using port ranges with hw-offload") Reported-by: Qiang Zhang <dtzq01@gmail.com> Closes: https://lore.kernel.org/netdev/CAPx+-5uvFxkhkz4=j_Xuwkezjn9U6kzKTD5jz4tZ9msSJ0fOJA@mail.gmail.com/ Cc: Yoshiki Komachi <komachi.yoshiki@gmail.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Jiri Pirko <jiri@resnulli.us> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20250218043210.732959-2-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
====================
gtp/geneve: Suppress list_del() splat during ->exit_batch_rtnl().
The common pattern in tunnel device's ->exit_batch_rtnl() is iterating
two netdev lists for each netns: (i) for_each_netdev() to clean up
devices in the netns, and (ii) the device type specific list to clean
up devices in other netns.
Then, ->exit_batch_rtnl() could touch the same device twice.
Say we have two netns A & B and device B that is created in netns A and
moved to netns B.
1. cleanup_net() processes netns A and then B.
2. ->exit_batch_rtnl() finds the device B while iterating netns A's (ii)
[ device B is not yet unlinked from netns B as
unregister_netdevice_many() has not been called. ]
3. ->exit_batch_rtnl() finds the device B while iterating netns B's (i)
gtp and geneve calls ->dellink() at 2. and 3. that calls list_del() for (ii)
and unregister_netdevice_queue().
Calling unregister_netdevice_queue() twice is fine because it uses
list_move_tail(), but the 2nd list_del() triggers a splat when
CONFIG_DEBUG_LIST is enabled.
Possible solution is either of
(a) Use list_del_init() in ->dellink()
(b) Iterate dev with empty ->unreg_list for (i) like
#define for_each_netdev_alive(net, d) \
list_for_each_entry(d, &(net)->dev_base_head, dev_list) \
if (list_empty(&d->unreg_list))
(c) Remove (i) and delegate it to default_device_exit_batch().
This series avoids the 2nd ->dellink() by (c) to suppress the splat for
gtp and geneve.
Note that IPv4/IPv6 tunnels calls just unregister_netdevice() during
->exit_batch_rtnl() and dev is unlinked from (ii) later in ->ndo_uninit(),
so they are safe.
Also, pfcp has the same pattern but is safe because
unregister_netdevice_many() is called for each netns.
====================
Kuniyuki Iwashima [Mon, 17 Feb 2025 20:37:05 +0000 (12:37 -0800)]
geneve: Suppress list corruption splat in geneve_destroy_tunnels().
As explained in the previous patch, iterating for_each_netdev() and
gn->geneve_list during ->exit_batch_rtnl() could trigger ->dellink()
twice for the same device.
If CONFIG_DEBUG_LIST is enabled, we will see a list_del() corruption
splat in the 2nd call of geneve_dellink().
Let's remove for_each_netdev() in geneve_destroy_tunnels() and delegate
that part to default_device_exit_batch().
Kuniyuki Iwashima [Mon, 17 Feb 2025 20:37:04 +0000 (12:37 -0800)]
gtp: Suppress list corruption splat in gtp_net_exit_batch_rtnl().
Brad Spengler reported the list_del() corruption splat in
gtp_net_exit_batch_rtnl(). [0]
Commit eb28fd76c0a0 ("gtp: Destroy device along with udp socket's netns
dismantle.") added the for_each_netdev() loop in gtp_net_exit_batch_rtnl()
to destroy devices in each netns as done in geneve and ip tunnels.
However, this could trigger ->dellink() twice for the same device during
->exit_batch_rtnl().
Say we have two netns A & B and gtp device B that resides in netns B but
whose UDP socket is in netns A.
1. cleanup_net() processes netns A and then B.
2. gtp_net_exit_batch_rtnl() finds the device B while iterating
netns A's gn->gtp_dev_list and calls ->dellink().
[ device B is not yet unlinked from netns B
as unregister_netdevice_many() has not been called. ]
3. gtp_net_exit_batch_rtnl() finds the device B while iterating
netns B's for_each_netdev() and calls ->dellink().
gtp_dellink() cleans up the device's hash table, unlinks the dev from
gn->gtp_dev_list, and calls unregister_netdevice_queue().
Basically, calling gtp_dellink() multiple times is fine unless
CONFIG_DEBUG_LIST is enabled.
Let's remove for_each_netdev() in gtp_net_exit_batch_rtnl() and
delegate the destruction to default_device_exit_batch() as done
in bareudp.
Linus Torvalds [Thu, 20 Feb 2025 02:11:28 +0000 (18:11 -0800)]
Merge tag 'mm-hotfixes-stable-2025-02-19-17-49' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"18 hotfixes. 5 are cc:stable and the remainder address post-6.13
issues or aren't considered necessary for -stable kernels.
10 are for MM and 8 are for non-MM. All are singletons, please see the
changelogs for details"
* tag 'mm-hotfixes-stable-2025-02-19-17-49' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
test_xarray: fix failure in check_pause when CONFIG_XARRAY_MULTI is not defined
kasan: don't call find_vm_area() in a PREEMPT_RT kernel
MAINTAINERS: update Nick's contact info
selftests/mm: fix check for running THP tests
mm: hugetlb: avoid fallback for specific node allocation of 1G pages
memcg: avoid dead loop when setting memory.max
mailmap: update Nick's entry
mm: pgtable: fix incorrect reclaim of non-empty PTE pages
taskstats: modify taskstats version
getdelays: fix error format characters
mm/migrate_device: don't add folio to be freed to LRU in migrate_device_finalize()
tools/mm: fix build warnings with musl-libc
mailmap: add entry for Feng Tang
.mailmap: add entries for Jeff Johnson
mm,madvise,hugetlb: check for 0-length range after end address adjustment
mm/zswap: fix inconsistency when zswap_store_page() fails
lib/iov_iter: fix import_iovec_ubuf iovec management
procfs: fix a locking bug in a vmcore_add_device_dump() error path
Jordan Rome [Thu, 13 Feb 2025 15:21:24 +0000 (07:21 -0800)]
bpf: Add bpf_copy_from_user_task_str() kfunc
This new kfunc will be able to copy a zero-terminated C strings from
another task's address space. This is similar to `bpf_copy_from_user_str()`
but reads memory of specified task.
Jordan Rome [Thu, 13 Feb 2025 15:21:23 +0000 (07:21 -0800)]
mm: Add copy_remote_vm_str() for readng C strings from remote VM
Similar to `access_process_vm()` but specific to strings. Also chunks
reads by page and utilizes `strscpy()` for handling null termination.
The primary motivation for this change is to copy strings from
a non-current task/process in BPF. There is already a helper
`bpf_copy_from_user_task()`, which uses `access_process_vm()` but one to
handle strings would be very helpful.
selftests/bpf: Enable kprobe_multi tests for ARM64
The kprobe_multi feature was disabled on ARM64 due to the lack of fprobe
support.
The fprobe rewrite on function_graph has been recently merged and thus
brought support for fprobes on arm64. This then enables kprobe_multi
support on arm64, and so the corresponding tests can now be run on this
architecture.
Remove the tests depending on kprobe_multi from DENYLIST.aarch64 to
allow those to run in CI. CONFIG_FPROBE is already correctly set in
tools/testing/selftests/bpf/config
We had some error handling confusion here;
-BCH_ERR_missing_indirect_extent is thrown by
trans_trigger_reflink_p_segment(); at this point we haven't decide
whether we're generating an error.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Kent Overstreet [Thu, 13 Feb 2025 17:43:42 +0000 (12:43 -0500)]
bcachefs: Fix fsck directory i_size checking
Error handling was wrong, causing unhandled transaction restart errors.
check_directory_size() was also inefficient, since keys in multiple
snapshots would be iterated over once for every snapshot. Convert it to
the same scheme used for i_sectors and subdir count checking.
Cc: Hongbo Li <lihongbo22@huawei.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
====================
Both tc_links.c and tc_opts.c do their tests on the loopback interface.
It prevents from parallelizing their executions.
Add a new behaviour to the test_progs framework that creates and opens a
new network namespace to run a test in it. This is done automatically on
tests whose names start with 'ns_'.
One test already has a name starting with 'ns_', so PATCH 1 renames it
to avoid conflicts. PATCH 2 introduces the test_progs 'feature'.
PATCH 3 & 4 convert some tests to use these dedicated namespaces.
Signed-off-by: Bastien Curutchet (eBPF Foundation) <bastien.curutchet@bootlin.com>
Changes in v2:
- Handle the netns creation / opening directly in test_progs
- Link to v1: https://lore.kernel.org/bpf/e3838d93-04e3-4e96-af53-e9e63550d7ba@bootlin.com
====================
selftests/bpf: ns_current_pid_tgid: Use test_progs's ns_ feature
Two subtests use the test_in_netns() function to run the test in a
dedicated network namespace. This can now be done directly through the
test_progs framework with a test name starting with 'ns_'.
Replace the use of test_in_netns() by test_ns_* calls.
Tests are serialized because they all use the loopback interface.
Replace the 'serial_test_' prefixes with 'test_ns_' to benefit from the
new test_prog feature which creates a dedicated namespace for each test,
allowing them to run in parallel.
selftests/bpf: Optionally open a dedicated namespace to run test in it
Some tests are serialized to prevent interference with others.
Open a dedicated network namespace when a test name starts with 'ns_' to
allow more test parallelization. Use the test name as namespace name to
avoid conflict between namespaces.
selftests/bpf: ns_current_pid_tgid: Rename the test function
Next patch will add a new feature to test_prog to run tests in a
dedicated namespace if the test name starts with 'ns_'. Here the test
name already starts with 'ns_' and creates some namespaces which would
conflict with the new feature.
cifs: Treat unhandled directory name surrogate reparse points as mount directory nodes
If the reparse point was not handled (indicated by the -EOPNOTSUPP from
ops->parse_reparse_point() call) but reparse tag is of type name surrogate
directory type, then treat is as a new mount point.
Name surrogate reparse point represents another named entity in the system.
From SMB client point of view, this another entity is resolved on the SMB
server, and server serves its content automatically. Therefore from Linux
client point of view, this name surrogate reparse point of directory type
crosses mount point.
Signed-off-by: Pali Rohár <pali@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com>
Steve French [Mon, 17 Feb 2025 04:17:54 +0000 (22:17 -0600)]
smb311: failure to open files of length 1040 when mounting with SMB3.1.1 POSIX extensions
If a file size has bits 0x410 = ATTR_DIRECTORY | ATTR_REPARSE set
then during queryinfo (stat) the file is regarded as a directory
and subsequent opens can fail. A simple test example is trying
to open any file 1040 bytes long when mounting with "posix"
(SMB3.1.1 POSIX/Linux Extensions).
The cause of this bug is that Attributes field in smb2_file_all_info
struct occupies the same place that EndOfFile field in
smb311_posix_qinfo, and sometimes the latter struct is incorrectly
processed as if it was the first one.
Reported-by: Oleh Nykyforchyn <oleh.nyk@gmail.com> Tested-by: Oleh Nykyforchyn <oleh.nyk@gmail.com> Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Cc: stable@vger.kernel.org Signed-off-by: Steve French <stfrench@microsoft.com>
-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.
So, in order to avoid ending up with flexible-array members in the
middle of other structs, we use the `__struct_group()` helper to
separate the flexible arrays from the rest of the members in the
flexible structures. We then use the newly created tagged `struct
smb2_file_link_info_hdr` and `struct smb2_file_rename_info_hdr`
to replace the type of the objects causing trouble: `rename_info`
and `link_info` in `struct smb2_compound_vars`.
We also want to ensure that when new members need to be added to the
flexible structures, they are always included within the newly created
tagged structs. For this, we use `static_assert()`. This ensures that the
memory layout for both the flexible structure and the new tagged struct
is the same after any changes.
So, with these changes, fix 86 of the following warnings:
fs/smb/client/cifsglob.h:2335:36: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
fs/smb/client/cifsglob.h:2334:38: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com> Signed-off-by: Steve French <stfrench@microsoft.com>
====================
This patch set fixes a bug in copy_verifier_state() where the
loop_entry field was not copied. This omission led to incorrect
loop_entry fields remaining in env->cur_state, causing incorrect
decisions about loop entry assignments in update_loop_entry().
An example of an unsafe program accepted by the verifier due to this
bug can be found in patch #2. This bug can also cause an infinite loop
in the verifier, see patch #5.
Structure of the patch set:
- Patch #1 fixes the bug but has a significant negative impact on
verification performance for sched_ext programs.
- Patch #3 mitigates the verification performance impact of patch #1
by avoiding clean_live_states() for states whose loop_entry is still
being verified. This reduces the number of processed instructions
for sched_ext programs by 28–92% in some cases.
- Patches #5-6 simplify {get,update}_loop_entry() logic (and are not
strictly necessary).
- Patches #7–10 mitigate the memory overhead introduced by patch #1
when a program with iterator-based loop hits the 1M instruction
limit. This is achieved by freeing states in env->free_list when
their branches and used_as_loop_entry counts reach zero.
Patches #1-4 were previously sent as a part of [1].
Eduard Zingerman [Sat, 15 Feb 2025 11:04:00 +0000 (03:04 -0800)]
bpf: free verifier states when they are no longer referenced
When fixes from patches 1 and 3 are applied, Patrick Somaru reported
an increase in memory consumption for sched_ext iterator-based
programs hitting 1M instructions limit. For example, 2Gb VMs ran out
of memory while verifying a program. Similar behaviour could be
reproduced on current bpf-next master.
Here is an example of such program:
/* verification completes if given 16G or RAM,
* final env->free_list size is 369,960 entries.
*/
SEC("raw_tp")
__flag(BPF_F_TEST_STATE_FREQ)
__success
int free_list_bomb(const void *ctx)
{
volatile char buf[48] = {};
unsigned i, j;
j = 0;
bpf_for(i, 0, 10) {
/* this forks verifier state:
* - verification of current path continues and
* creates a checkpoint after 'if';
* - verification of forked path hits the
* checkpoint and marks it as loop_entry.
*/
if (bpf_get_prandom_u32())
asm volatile ("");
/* this marks 'j' as precise, thus any checkpoint
* created on current iteration would not be matched
* on the next iteration.
*/
buf[j++] = 42;
j %= ARRAY_SIZE(buf);
}
asm volatile (""::"r"(buf));
return 0;
}
Memory consumption increased due to more states being marked as loop
entries and eventually added to env->free_list.
This commit introduces logic to free states from env->free_list during
verification. A state in env->free_list can be freed if:
- it has no child states;
- it is not used as a loop_entry.
This commit:
- updates bpf_verifier_state->used_as_loop_entry to be a counter
that tracks how many states use this one as a loop entry;
- adds a function maybe_free_verifier_state(), which:
- frees a state if its ->branches and ->used_as_loop_entry counters
are both zero;
- if the state is freed, state->loop_entry->used_as_loop_entry is
decremented, and an attempt is made to free state->loop_entry.
In the example above, this approach reduces the maximum number of
states in the free list from 369,960 to 16,223.
However, this approach has its limitations. If the buf size in the
example above is modified to 64, state caching overflows: the state
for j=0 is evicted from the cache before it can be used to stop
traversal. As a result, states in the free list accumulate because
their branch counters do not reach zero.
The effect of this patch on the selftests looks as follows:
Eduard Zingerman [Sat, 15 Feb 2025 11:03:59 +0000 (03:03 -0800)]
bpf: use list_head to track explored states and free list
The next patch in the set needs the ability to remove individual
states from env->free_list while only holding a pointer to the state.
Which requires env->free_list to be a doubly linked list.
This patch converts env->free_list and struct bpf_verifier_state_list
to use struct list_head for this purpose. The change to
env->explored_states is collateral.
Eduard Zingerman [Sat, 15 Feb 2025 11:03:58 +0000 (03:03 -0800)]
bpf: do not update state->loop_entry in get_loop_entry()
The patch 9 is simpler if less places modify loop_entry field.
The loop deleted by this patch does not affect correctness, but is a
performance optimization. However, measurements on selftests and
sched_ext programs show that this optimization is unnecessary:
- at most 2 steps are done in get_loop_entry();
- most of the time 0 or 1 steps are done in get_loop_entry().
Measured using "do-not-submit" patches from here:
https://github.com/eddyz87/bpf/tree/get-loop-entry-hungup
Eduard Zingerman [Sat, 15 Feb 2025 11:03:57 +0000 (03:03 -0800)]
bpf: make state->dfs_depth < state->loop_entry->dfs_depth an invariant
For a generic loop detection algorithm a graph node can be a loop
header for itself. However, state loop entries are computed for use in
is_state_visited(), where get_loop_entry(state)->branches is checked.
is_state_visited() also checks state->branches, thus the case when
state == state->loop_entry is not interesting for is_state_visited().
This change does not affect correctness, but simplifies
get_loop_entry() a bit and also simplifies change to
update_loop_entry() in patch 9.
Eduard Zingerman [Sat, 15 Feb 2025 11:03:56 +0000 (03:03 -0800)]
bpf: detect infinite loop in get_loop_entry()
Tejun Heo reported an infinite loop in get_loop_entry(),
when verifying a sched_ext program layered_dispatch in [1].
After some investigation I'm sure that root cause is fixed by patches
1,3 in this patch-set.
To err on the safe side, this commit modifies get_loop_entry() to
detect infinite loops and abort verification in such cases.
The number of steps get_loop_entry(S) can make while moving along the
bpf_verifier_state->loop_entry chain is bounded by the DFS depth of
state S. This fact is exploited to implement the check.
To avoid dealing with the potential error code returned from
get_loop_entry() in update_loop_entry(), remove the get_loop_entry()
calls there:
- This change does not affect correctness. Loop entries would still be
updated during the backward DFS move in update_branch_counts().
- This change does not affect performance. Measurements show that
get_loop_entry() performs at most 1 step on selftests and at most 2
steps on sched_ext programs (1 step in 17 cases, 2 steps in 3
cases, measured using "do-not-submit" patches from [2]).
Assuming that verifier.c:clean_live_states() operates w/o change from
the previous patch (e.g. as on current master) verification would
proceed as follows:
- at (1) state {buf[0]=?,o=drained}:
- checkpoint
- push visit to (2) for later
- at (4) {buf[0]=?,o=drained}
- pop (2) {buf[0]=?,o=active}, push visit to (3) for later
- at (1) {buf[0]=?,o=active}
- checkpoint
- push visit to (2) for later
- at (4) {buf[0]=?,o=drained}
- pop (2) {buf[0]=?,o=active}, push visit to (3) for later
- at (1) {buf[0]=?,o=active}:
- checkpoint reached, checkpoint's branch count becomes 0
- checkpoint is processed by clean_live_states() and
becomes {o=active}
- pop (3) {buf[0]=42,o=active}
- at (1), {buf[0]=42,o=active}
- checkpoint
- push visit to (2) for later
- at (4) {buf[0]=42,o=drained}
- pop (2) {buf[0]=42,o=active}, push visit to (3) for later
- at (1) {buf[0]=42,o=active}, checkpoint reached
- pop (3) {buf[0]=42,o=active}
- at (1) {buf[0]=42,o=active}:
- checkpoint reached, checkpoint's branch count becomes 0
- checkpoint is processed by clean_live_states() and
becomes {o=active}
- ...
Note how clean_live_states() converted the checkpoint
{buf[0]=42,o=active} to {o=active} and it can no longer be matched
against {buf[0]=<any>,o=active}, because iterator based states
are compared using stacksafe(... RANGE_WITHIN), that requires
stack slots to have same types. At the same time there are
still states {buf[0]=42,o=active} pushed to DFS stack.
Eduard Zingerman [Sat, 15 Feb 2025 11:03:54 +0000 (03:03 -0800)]
bpf: don't do clean_live_states when state->loop_entry->branches > 0
verifier.c:is_state_visited() uses RANGE_WITHIN states comparison rules
for cached states that have loop_entry with non-zero branches count
(meaning that loop_entry's verification is not yet done).
The RANGE_WITHIN rules in regsafe()/stacksafe() require register and
stack objects types to be identical in current and old states.
verifier.c:clean_live_states() replaces registers and stack spills
with NOT_INIT/STACK_INVALID marks, if these registers/stack spills are
not read in any child state. This means that clean_live_states() works
against loop convergence logic under some conditions. See selftest in
the next patch for a specific example.
Mitigate this by prohibiting clean_verifier_state() when
state->loop_entry->branches > 0.
This undoes negative verification performance impact of the
copy_verifier_state() fix from the previous patch.
Below is comparison between master and current patch.
Eduard Zingerman [Sat, 15 Feb 2025 11:03:53 +0000 (03:03 -0800)]
selftests/bpf: test correct loop_entry update in copy_verifier_state
A somewhat cumbersome test case sensitive to correct copying of
bpf_verifier_state->loop_entry fields in
verifier.c:copy_verifier_state().
W/o the fix from a previous commit the program is accepted as safe.
1: /* poison block */
2: if (random() != 24) { // assume false branch is placed first
3: i = iter_new();
4: while (iter_next(i));
5: iter_destroy(i);
6: return;
7: }
8:
9: /* dfs_depth block */
10: for (i = 10; i > 0; i--);
11:
12: /* main block */
13: i = iter_new(); // fp[-16]
14: b = -24; // r8
15: for (;;) {
16: if (iter_next(i))
17: break;
18: if (random() == 77) { // assume false branch is placed first
19: *(u64 *)(r10 + b) = 7; // this is not safe when b == -25
20: iter_destroy(i);
21: return;
22: }
23: if (random() == 42) { // assume false branch is placed first
24: b = -25;
25: }
26: }
27: iter_destroy(i);
The goal of this example is to:
(a) poison env->cur_state->loop_entry with a state S,
such that S->branches == 0;
(b) set state S as a loop_entry for all checkpoints in
/* main block */, thus forcing NOT_EXACT states comparisons;
(c) exploit incorrect loop_entry set for checkpoint at line 18
by first creating a checkpoint with b == -24 and then
pruning the state with b == -25 using that checkpoint.
The /* poison block */ is responsible for goal (a).
It forces verifier to first validate some unrelated iterator based
loop, which leads to an update_loop_entry() call in is_state_visited(),
which places checkpoint created at line 4 as env->cur_state->loop_entry.
Starting from line 8, the branch count for that checkpoint is 0.
The /* dfs_depth block */ is responsible for goal (b).
It abuses the fact that update_loop_entry(cur, hdr) only updates
cur->loop_entry when hdr->dfs_depth <= cur->dfs_depth.
After line 12 every state has dfs_depth bigger then dfs_depth of
poisoned env->cur_state->loop_entry. Thus the above condition is never
true for lines 12-27.
The /* main block */ is responsible for goal (c).
Verification proceeds as follows:
- checkpoint {b=-24,i=active} created at line 16;
- jump 18->23 is verified first, jump to 19 pushed to stack;
- jump 23->26 is verified first, jump to 24 pushed to stack;
- checkpoint {b=-24,i=active} created at line 15;
- current state is pruned by checkpoint created at line 16,
this sets branches count for checkpoint at line 15 to 0;
- jump to 24 is popped from stack;
- line 16 is reached in state {b=-25,i=active};
- this is pruned by a previous checkpoint {b=-24,i=active}:
- checkpoint's loop_entry is poisoned and has branch count of 0,
hence states are compared using NOT_EXACT rules;
- b is not marked precise yet.
Eduard Zingerman [Sat, 15 Feb 2025 11:03:52 +0000 (03:03 -0800)]
bpf: copy_verifier_state() should copy 'loop_entry' field
The bpf_verifier_state.loop_entry state should be copied by
copy_verifier_state(). Otherwise, .loop_entry values from unrelated
states would poison env->cur_state.
Additionally, env->stack should not contain any states with
.loop_entry != NULL. The states in env->stack are yet to be verified,
while .loop_entry is set for states that reached an equivalent state.
This means that env->cur_state->loop_entry should always be NULL after
pop_stack().
See the selftest in the next commit for an example of the program that
is not safe yet is accepted by verifier w/o this fix.
This change has some verification performance impact for selftests:
====================
net: Fix race of rtnl_net_lock(dev_net(dev)).
Yael Chemla reported that commit 7fb1073300a2 ("net: Hold rtnl_net_lock()
in (un)?register_netdevice_notifier_dev_net().") started to trigger KASAN's
use-after-free splat.
The problem is that dev_net(dev) fetched before rtnl_net_lock() might be
different after rtnl_net_lock().
The patch 2 fixes the issue by checking dev_net(dev) after rtnl_net_lock(),
and the patch 3 fixes the same potential issue that would emerge once RTNL
is removed.
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