diff options
| author | Dave Marchevsky <davemarchevsky@fb.com> | 2023-04-24 13:43:21 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-04-24 14:02:11 -0700 |
| commit | 7deca5eae83389ca40ac1b1bde96e4af17cca84f (patch) | |
| tree | 3177280c48b4814b2acc4f88eeccb40770e3c296 /kernel | |
| parent | 35150203e30b52d657165e325e3abc3b29c2086d (diff) | |
bpf: Disable bpf_refcount_acquire kfunc calls until race conditions are fixed
As reported by Kumar in [0], the shared ownership implementation for BPF
programs has some race conditions which need to be addressed before it
can safely be used. This patch does so in a minimal way instead of
ripping out shared ownership entirely, as proper fixes for the issues
raised will follow ASAP, at which point this patch's commit can be
reverted to re-enable shared ownership.
The patch removes the ability to call bpf_refcount_acquire_impl from BPF
programs. Programs can only bump refcount and obtain a new owning
reference using this kfunc, so removing the ability to call it
effectively disables shared ownership.
Instead of changing success / failure expectations for
bpf_refcount-related selftests, this patch just disables them from
running for now.
[0]: https://lore.kernel.org/bpf/d7hyspcow5wtjcmw4fugdgyp3fwhljwuscp3xyut5qnwivyeru@ysdq543otzv2/
Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230424204321.2680232-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0d73139ee4d8..5c4aa393f65a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10509,7 +10509,10 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_ verbose(env, "arg#%d doesn't point to a type with bpf_refcount field\n", i); return -EINVAL; } - + if (rec->refcount_off >= 0) { + verbose(env, "bpf_refcount_acquire calls are disabled for now\n"); + return -EINVAL; + } meta->arg_refcount_acquire.btf = reg->btf; meta->arg_refcount_acquire.btf_id = reg->btf_id; break; |