]> www.infradead.org Git - users/jedix/linux-maple.git/commit
bpf: Specify access type of bpf_sysctl_get_name args
authorJerome Marchand <jmarchan@redhat.com>
Thu, 19 Jun 2025 14:06:02 +0000 (16:06 +0200)
committerAlexei Starovoitov <ast@kernel.org>
Tue, 24 Jun 2025 04:50:44 +0000 (21:50 -0700)
commit2eb7648558a7911f2208e8940cd22ca40e93cc76
tree72d94d14f85aebfe38fbd964ae19ec8d4d2c1020
parentaa485e8789d56a4573f7c8d000a182b749eaa64d
bpf: Specify access type of bpf_sysctl_get_name args

The second argument of bpf_sysctl_get_name() helper is a pointer to a
buffer that is being written to. However that isn't specify in the
prototype.

Until commit 37cce22dbd51a ("bpf: verifier: Refactor helper access
type tracking"), all helper accesses were considered as a possible
write access by the verifier, so no big harm was done. However, since
then, the verifier might make wrong asssumption about the content of
that address which might lead it to make faulty optimizations (such as
removing code that was wrongly labeled dead). This is what happens in
test_sysctl selftest to the tests related to sysctl_get_name.

Add MEM_WRITE flag the second argument of bpf_sysctl_get_name().

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250619140603.148942-2-jmarchan@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
kernel/bpf/cgroup.c