diff options
| author | Amery Hung <ameryhung@gmail.com> | 2025-11-26 12:29:26 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-11-28 15:18:28 -0800 |
| commit | b4bf1d23dc1da236c92a9d9be68cc63358d1f750 (patch) | |
| tree | aa7657f5b2f59e28de8837e79a422b1fa1440e15 /kernel/bpf/bpf_lsm.c | |
| parent | 19f4091bf2679759da877eb23a37863dc4368441 (diff) | |
bpf: Disable file_alloc_security hook
A use-after-free bug may be triggered by calling bpf_inode_storage_get()
in a BPF LSM program hooked to file_alloc_security. Disable the hook to
prevent this from happening.
The cause of the bug is shown in the trace below. In alloc_file(), a
file struct is first allocated through kmem_cache_alloc(). Then,
file_alloc_security hook is invoked. Since the zero initialization or
assignment of f->f_inode happen after this LSM hook, a BPF program may
get a dangeld inode pointer by walking the file struct.
alloc_file()
-> alloc_empty_file()
-> f = kmem_cache_alloc()
-> init_file()
-> security_file_alloc() // f->f_inode not init-ed yet!
-> f->f_inode = NULL;
-> file_init_path()
-> f->f_inode = path->dentry->d_inode
Reported-by: Kaiyan Mei <M202472210@hust.edu.cn>
Reported-by: Yinhao Hu <dddddd@hust.edu.cn>
Reported-by: Dongliang Mu <dzm91@hust.edu.cn>
Closes: https://lore.kernel.org/bpf/1d2d1968.47cd3.19ab9528e94.Coremail.kaiyanm@hust.edu.cn/
Signed-off-by: Amery Hung <ameryhung@gmail.com>
Link: https://lore.kernel.org/r/20251126202927.2584874-1-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/bpf_lsm.c')
| -rw-r--r-- | kernel/bpf/bpf_lsm.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 0a59df1c550a..7cb6e8d4282c 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -51,6 +51,7 @@ BTF_ID(func, bpf_lsm_key_getsecurity) BTF_ID(func, bpf_lsm_audit_rule_match) #endif BTF_ID(func, bpf_lsm_ismaclabel) +BTF_ID(func, bpf_lsm_file_alloc_security) BTF_SET_END(bpf_lsm_disabled_hooks) /* List of LSM hooks that should operate on 'current' cgroup regardless |