Re: [PATCH v3 1/9] perf evsel: Clamp sample_id size for ksymbol, bpf, and text_poke events

[sashiko-bot@kernel.org]

> On kernels without the fix ("perf/core: Restore header fields in
> sideband output callbacks") to restore event_id.header.size in
> perf_event_ksymbol_output(), perf_event_bpf_output(), and
> perf_event_text_poke_output(), concurrent perf sessions cause those
> sideband records to be emitted with header.size inflated by multiple
> id_header_size increments while the single id_sample is written
> immediately after the event payload. Indexing backwards from
> event->header.size reads uninitialized ring-buffer bytes at the end of
> the record, causing evlist__event2evsel() to fail with -EFAULT.
> 
> Add evsel__event_size() to clamp the effective size used to locate the
> trailing id_sample for PERF_RECORD_KSYMBOL, PERF_RECORD_BPF_EVENT, and
> PERF_RECORD_TEXT_POKE to payload + id_hdr_size while leaving
> event->header.size intact for advancing the ring-buffer/file stream.
> 
> Fixes: 9aa0bfa370b2 ("perf tools: Handle PERF_RECORD_KSYMBOL")
> Fixes: 45178a928a4b ("perf tools: Handle PERF_RECORD_BPF_EVENT")
> Fixes: 246eba8e9041 ("perf tools: Add support for PERF_RECORD_TEXT_POKE")
> Link: https://lore.kernel.org/r/20260929014206.4175245-1-irogers@google.com
> Assisted-by: Antigravity:gemini-3.1-pro
> Signed-off-by: Ian Rogers <irogers@google.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260929065839.407062-1-irogers@google.com?part=1