Re: [PATCH] bpf: fix unitialized warning

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri,  3 Jul 2026 21:03:22 -0700
Stephen Hemminger <stephen@networkplumber.org> wrote:

> Coverity complains unitialized use of structure.
> 
> Coverity ID: 504611
> Fixes: 17509d474226 ("bpf/validate: fix BPF_ADD of pointer to a scalar")
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---

Ignore AI review of this patch. The CI AI review is using weak AI
model and no tooling; it ends up hallucinating about code that doesn't exist.
Better AI reviewing the reviewer sees...

Coverity 504611 is a true positive. eval_fill_max_bound() sets u, s,
v.type, and mask, but not v.size or v.buf_size. In eval_add() the
pointer+pointer path does eval_fill_max_bound(&rs_buf, msk); *rd =
rs_buf; on a fresh local, so the struct copy propagates the
uninitialized v.size/v.buf_size. Zero-init at declaration closes
exactly that.

The AI review is quoting code that isn't there. eval_add() has no
rs_buf = *rs; and no eval_apply_mask(&rs_buf, ...) call. That snippet
looks reconstructed from the diff hunk header (eval_apply_mask, the
preceding function) rather than the function actually being patched.
Its central claim, that rs_buf is only touched via rs = &rs_buf inside
the if, is wrong: the uninitialized read is the *rd = rs_buf copy, and
rs then reads it after the block.