[PATCH 01/25] perf/core: Reject non-positive AUX snapshot sizes
From: Leo Yan <leo.yan@arm.com>
Date: 2026-09-15 15:49:29
Also in:
linux-arm-kernel, linux-doc, lkml
Subsystem:
performance events subsystem, the rest · Maintainers:
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds
The existing validation rejects negative copy errors but allows a zero
return. In that case no AUX data was copied, but it is incorrectly
passed to the alignment-padding check.
Reject zero together with negative errors before calculating the padding.
This reports the invalid snapshot result and avoids treating a missing
AUX payload as alignment padding.
Fixes: a4faf00d994c ("perf/aux: Allow using AUX data in perf samples")
Assisted-by: Codex:gpt-6
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
kernel/events/core.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index fe33fe15689d077e7f445c0b17d9c2e638c884a1..17355e4b8b7c6c106117153c9eb8509e6f9a41e3 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c@@ -8058,12 +8058,11 @@ static void perf_aux_sample_output(struct perf_event *event, size = perf_pmu_snapshot_aux(rb, sampler, handle, data->aux_size); /* - * An error here means that perf_output_copy() failed (returned a - * non-zero surplus that it didn't copy), which in its current - * enlightened implementation is not possible. If that changes, we'd - * like to know. + * A negative return means that perf_output_copy() failed, while zero + * means that no AUX data was copied despite a non-zero request. Neither + * can be treated as alignment padding below. */ - if (WARN_ON_ONCE(size < 0)) + if (WARN_ON_ONCE(size <= 0)) goto out_put; /*
--
2.34.1