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Message-ID: <aLdnq7EayjFVbGYp@google.com>
Date: Tue, 2 Sep 2025 14:54:51 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Kan Liang <kan.liang@...ux.intel.com>,
Blake Jones <blakejones@...gle.com>,
Zhongqiu Han <quic_zhonhan@...cinc.com>,
Andrii Nakryiko <andrii@...nel.org>,
Song Liu <songliubraving@...com>,
Dave Marchevsky <davemarchevsky@...com>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org, Howard Chu <howardchu95@...il.com>,
song@...nel.org, Yonghong Song <yonghong.song@...ux.dev>
Subject: Re: [PATCH v1 0/3] Fix use-after-free race in bpf_prog_info synthesis
Hi Ian,
On Tue, Sep 02, 2025 at 11:17:10AM -0700, Ian Rogers wrote:
> The addition of more use of bpf_prog_info for gather BPF metadata in:
> https://lore.kernel.org/all/20250612194939.162730-1-blakejones@google.com/
> and the ever richer perf trace testing, such as:
> https://lore.kernel.org/all/20250528191148.89118-1-howardchu95@gmail.com/
> frequently triggered a latent perf bug in v6.17 when the perf and
> libbpf updates came together. The bug would cause segvs and was reported here:
> https://lore.kernel.org/lkml/CAP-5=fWJQcmUOP7MuCA2ihKnDAHUCOBLkQFEkQES-1ZZTrgf8Q@mail.gmail.com/
>
> To fix the issue the 1st and 3rd patch are necessary. Both patches
> address a race of either the sideband thread updating perf's state or
> the kernel state changing over two system calls.
Thanks a lot for the fix!
>
> The use-after-free was introduced by:
> https://lore.kernel.org/r/20241205084500.823660-4-quic_zhonhan@quicinc.com
> The lack of failing getting the bpf_prog_info for changes in the
> kernel was introduced in:
> https://lore.kernel.org/r/20211011082031.4148337-4-davemarchevsky@fb.com
>
> As v6.17 is currently actively segv-ing in perf test I'd recommend
> these patches go into v6.17 asap.
Sure, I'll add them to perf-tools tree.
>
> When running the perf tests on v6.17 I frequently see less critical
> test failures addressed in:
> https://lore.kernel.org/all/20250821221834.1312002-1-irogers@google.com/
Are they all from v6.17?
>
> Ian Rogers (3):
> perf bpf-event: Fix use-after-free in synthesis
> perf bpf-utils: Constify bpil_array_desc
> perf bpf-utils: Harden get_bpf_prog_info_linear
Reviewed-by: Namhyung Kim <namhyung@...nel.org>
Thanks,
Namhyung
>
> tools/perf/util/bpf-event.c | 39 ++++++++++++++++--------
> tools/perf/util/bpf-utils.c | 61 ++++++++++++++++++++++++-------------
> 2 files changed, 66 insertions(+), 34 deletions(-)
>
> --
> 2.51.0.355.g5224444f11-goog
>
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