bcachefs: Fix use after free

bcachefs: Fix use after free

acc->k.data should be used with the lock hold:

00221 ========= TEST   generic/187
00221        run fstests generic/187 at 2025-02-09 21:08:10
00221 spectre-v4 mitigation disabled by command-line option
00222 bcachefs (vdc): starting version 1.20: directory_size opts=errors=ro
00222 bcachefs (vdc): initializing new filesystem
00222 bcachefs (vdc): going read-write
00222 bcachefs (vdc): marking superblocks
00222 bcachefs (vdc): initializing freespace
00222 bcachefs (vdc): done initializing freespace
00222 bcachefs (vdc): reading snapshots table
00222 bcachefs (vdc): reading snapshots done
00222 bcachefs (vdc): done starting filesystem
00222 bcachefs (vdc): shutting down
00222 bcachefs (vdc): going read-only
00222 bcachefs (vdc): finished waiting for writes to stop
00223 bcachefs (vdc): flushing journal and stopping allocators, journal seq 6
00223 bcachefs (vdc): flushing journal and stopping allocators complete, journal seq 8
00223 bcachefs (vdc): clean shutdown complete, journal seq 9
00223 bcachefs (vdc): marking filesystem clean
00223 bcachefs (vdc): shutdown complete
00223 bcachefs (vdc): starting version 1.20: directory_size opts=errors=ro
00223 bcachefs (vdc): initializing new filesystem
00223 bcachefs (vdc): going read-write
00223 bcachefs (vdc): marking superblocks
00223 bcachefs (vdc): initializing freespace
00223 bcachefs (vdc): done initializing freespace
00223 bcachefs (vdc): reading snapshots table
00223 bcachefs (vdc): reading snapshots done
00223 bcachefs (vdc): done starting filesystem
00244 hrtimer: interrupt took 123350440 ns
00264 bcachefs (vdc): shutting down
00264 bcachefs (vdc): going read-only
00264 bcachefs (vdc): finished waiting for writes to stop
00264 bcachefs (vdc): flushing journal and stopping allocators, journal seq 97
00265 bcachefs (vdc): flushing journal and stopping allocators complete, journal seq 101
00265 bcachefs (vdc): clean shutdown complete, journal seq 102
00265 bcachefs (vdc): marking filesystem clean
00265 bcachefs (vdc): shutdown complete
00265 bcachefs (vdc): starting version 1.20: directory_size opts=errors=ro
00265 bcachefs (vdc): recovering from clean shutdown, journal seq 102
00265 bcachefs (vdc): accounting_read...
00265 ==================================================================
00265  done
00265 BUG: KASAN: slab-use-after-free in bch2_fs_to_text+0x12b4/0x1728
00265 bcachefs (vdc): alloc_read... done
00265 bcachefs (vdc): stripes_read... done
00265 Read of size 4 at addr ffffff80c57eac00 by task cat/7531
00265 bcachefs (vdc): snapshots_read... done
00265
00265 CPU: 6 UID: 0 PID: 7531 Comm: cat Not tainted 6.13.0-rc3-ktest-g16fc6fa3819d #14103
00265 Hardware name: linux,dummy-virt (DT)
00265 Call trace:
00265  show_stack+0x1c/0x30 (C)
00265  dump_stack_lvl+0x6c/0x80
00265  print_report+0xf8/0x5d8
00265  kasan_report+0x90/0xd0
00265  __asan_report_load4_noabort+0x1c/0x28
00265  bch2_fs_to_text+0x12b4/0x1728
00265  bch2_fs_show+0x94/0x188
00265  sysfs_kf_seq_show+0x1a4/0x348
00265  kernfs_seq_show+0x12c/0x198
00265  seq_read_iter+0x27c/0xfd0
00265  kernfs_fop_read_iter+0x390/0x4f8
00265  vfs_read+0x480/0x7f0
00265  ksys_read+0xe0/0x1e8
00265  __arm64_sys_read+0x70/0xa8
00265  invoke_syscall.constprop.0+0x74/0x1e8
00265  do_el0_svc+0xc8/0x1c8
00265  el0_svc+0x20/0x60
00265  el0t_64_sync_handler+0x104/0x130
00265  el0t_64_sync+0x154/0x158
00265
00265 Allocated by task 7510:
00265  kasan_save_stack+0x28/0x50
00265  kasan_save_track+0x1c/0x38
00265  kasan_save_alloc_info+0x3c/0x50
00265  __kasan_kmalloc+0xac/0xb0
00265  __kmalloc_node_noprof+0x168/0x348
00265  __kvmalloc_node_noprof+0x20/0x140
00265  __bch2_darray_resize_noprof+0x90/0x1b0
00265  __bch2_accounting_mem_insert+0x76c/0xb08
00265  bch2_accounting_mem_insert+0x224/0x3b8
00265  bch2_accounting_mem_mod_locked+0x480/0xc58
00265  bch2_accounting_read+0xa94/0x3eb8
00265  bch2_run_recovery_pass+0x80/0x178
00265  bch2_run_recovery_passes+0x340/0x698
00265  bch2_fs_recovery+0x1c98/0x2bd8
00265  bch2_fs_start+0x240/0x490
00265  bch2_fs_get_tree+0xe1c/0x1458
00265  vfs_get_tree+0x7c/0x250
00265  path_mount+0xe24/0x1648
00265  __arm64_sys_mount+0x240/0x438
00265  invoke_syscall.constprop.0+0x74/0x1e8
00265  do_el0_svc+0xc8/0x1c8
00265  el0_svc+0x20/0x60
00265  el0t_64_sync_handler+0x104/0x130
00265  el0t_64_sync+0x154/0x158
00265
00265 Freed by task 7510:
00265  kasan_save_stack+0x28/0x50
00265  kasan_save_track+0x1c/0x38
00265  kasan_save_free_info+0x48/0x88
00265  __kasan_slab_free+0x48/0x60
00265  kfree+0x188/0x408
00265  kvfree+0x3c/0x50
00265  __bch2_darray_resize_noprof+0xe0/0x1b0
00265  __bch2_accounting_mem_insert+0x76c/0xb08
00265  bch2_accounting_mem_insert+0x224/0x3b8
00265  bch2_accounting_mem_mod_locked+0x480/0xc58
00265  bch2_accounting_read+0xa94/0x3eb8
00265  bch2_run_recovery_pass+0x80/0x178
00265  bch2_run_recovery_passes+0x340/0x698
00265  bch2_fs_recovery+0x1c98/0x2bd8
00265  bch2_fs_start+0x240/0x490
00265  bch2_fs_get_tree+0xe1c/0x1458
00265  vfs_get_tree+0x7c/0x250
00265  path_mount+0xe24/0x1648
00265 bcachefs (vdc): going read-write
00265  __arm64_sys_mount+0x240/0x438
00265  invoke_syscall.constprop.0+0x74/0x1e8
00265  do_el0_svc+0xc8/0x1c8
00265  el0_svc+0x20/0x60
00265  el0t_64_sync_handler+0x104/0x130
00265  el0t_64_sync+0x154/0x158
00265
00265 The buggy address belongs to the object at ffffff80c57eac00
00265  which belongs to the cache kmalloc-128 of size 128
00265 The buggy address is located 0 bytes inside of
00265  freed 128-byte region [ffffff80c57eac00, ffffff80c57eac80)
00265
00265 The buggy address belongs to the physical page:
00265 page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1057ea
00265 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
00265 flags: 0x8000000000000040(head|zone=2)
00265 page_type: f5(slab)
00265 raw: 8000000000000040 ffffff80c0002800 dead000000000100 dead000000000122
00265 raw: 0000000000000000 0000000000200020 00000001f5000000 ffffff80c57a6400
00265 head: 8000000000000040 ffffff80c0002800 dead000000000100 dead000000000122
00265 head: 0000000000000000 0000000000200020 00000001f5000000 ffffff80c57a6400
00265 head: 8000000000000001 fffffffec315fa81 ffffffffffffffff 0000000000000000
00265 head: 0000000000000002 0000000000000000 00000000ffffffff 0000000000000000
00265 page dumped because: kasan: bad access detected
00265
00265 Memory state around the buggy address:
00265  ffffff80c57eab00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00265  ffffff80c57eab80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
00265 >ffffff80c57eac00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
00265                    ^
00265  ffffff80c57eac80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
00265  ffffff80c57ead00: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
00265 ==================================================================
00265 Kernel panic - not syncing: kasan.fault=panic set ...
00265 CPU: 6 UID: 0 PID: 7531 Comm: cat Not tainted 6.13.0-rc3-ktest-g16fc6fa3819d #14103
00265 Hardware name: linux,dummy-virt (DT)
00265 Call trace:
00265  show_stack+0x1c/0x30 (C)
00265  dump_stack_lvl+0x30/0x80
00265  dump_stack+0x18/0x20
00265  panic+0x4d4/0x518
00265  start_report.constprop.0+0x0/0x90
00265  kasan_report+0xa0/0xd0
00265  __asan_report_load4_noabort+0x1c/0x28
00265  bch2_fs_to_text+0x12b4/0x1728
00265  bch2_fs_show+0x94/0x188
00265  sysfs_kf_seq_show+0x1a4/0x348
00265  kernfs_seq_show+0x12c/0x198
00265  seq_read_iter+0x27c/0xfd0
00265  kernfs_fop_read_iter+0x390/0x4f8
00265  vfs_read+0x480/0x7f0
00265  ksys_read+0xe0/0x1e8
00265  __arm64_sys_read+0x70/0xa8
00265  invoke_syscall.constprop.0+0x74/0x1e8
00265  do_el0_svc+0xc8/0x1c8
00265  el0_svc+0x20/0x60
00265  el0t_64_sync_handler+0x104/0x130
00265  el0t_64_sync+0x154/0x158
00265 SMP: stopping secondary CPUs
00265 Kernel Offset: disabled
00265 CPU features: 0x000,00000070,00000010,8240500b
00265 Memory Limit: none
00265 ---[ end Kernel panic - not syncing: kasan.fault=panic set ... ]---
00270 ========= FAILED TIMEOUT generic.187 in 1200s

Signed-off-by: Alan Huang <mmpgouride@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>