Re: [PATCH v2 bpf-next] bpf: Fix a potential use-after-free

[Anton Protopopov <a.s.protopopov@gmail.com>]

On 26/02/09 01:06PM, bot+bpf-ci@kernel.org wrote:
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index edf5342b982f..24de90357450 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -21333,29 +21333,28 @@ static int find_btf_percpu_datasec(struct btf *btf)
> >  }
> >
> >  /*
> > - * Add btf to the used_btfs array and return the index. (If the btf was
> > - * already added, then just return the index.) Upon successful insertion
> > - * increase btf refcnt, and, if present, also refcount the corresponding
> > - * kernel module.
> > + * Add btf to the used_btfs array and return the index. If needed, refcount the
> > + * corresponding kernel module. To simplify caller's error checking in case of
> > + * error or if btf was added before, decrease the btf refcount.
> >   */
> 
> The updated comment says "return the index" but the function now returns 0
> on success rather than the actual index. The old code returned
> env->used_btf_cnt++ (the index), but the new code returns 0:
> 
>     env->used_btf_cnt++;
>     return 0;
> 
> Should the comment say "return 0 on success" instead of "return the index"?

Yeah, thanks

> [ ... ]
> 
> 
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
> 
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21825693233
> 
> AI-authorship-score: low
> AI-authorship-explanation: The commit has standard kernel formatting, addresses a real syzbot-reported bug with proper attribution, and shows iterative development through review feedback, all consistent with human authorship.
> issues-found: 1
> issue-severity-score: low
> issue-severity-explanation: Minor documentation issue where a comment says 'return the index' but the function returns 0 on success; no runtime impact as no callers use the return value as an index.