From: Jiri Olsa <olsajiri@gmail.com>
To: Song Liu <song@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
stable@vger.kernel.org, bpf@vger.kernel.org,
Martin KaFai Lau <kafai@fb.com>,
Eduard Zingerman <eddyz87@gmail.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>
Subject: Re: [PATCH bpf 1/2] bpf: Do not release trampoline image in case off unregister error
Date: Sat, 25 Apr 2026 22:40:30 +0200 [thread overview]
Message-ID: <ae0mvi9yCiGakqdH@krava> (raw)
In-Reply-To: <CAPhsuW5rcXABPeOy7PFkHkO8WNyfqppGpB5ijTvmMbj7GVWfcg@mail.gmail.com>
On Fri, Apr 24, 2026 at 08:50:51AM -0700, Song Liu wrote:
> On Fri, Apr 24, 2026 at 8:39 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > If unregister_fentry fails we still have trampoline image attached
> > to a function, so releasing it could trigger crash. Releasing the
> > trampoline image only when the unregister succeeds.
> >
> > Cc: stable@vger.kernel.org
> > Fixes: e21aa341785c ("bpf: Fix fexit trampoline.")
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
>
> The fix looks good.
>
> Acked-by: Song Liu <song@kernel.org>
>
> Can we add a test case that triggers this crash without the fix?
I don't about valid scenario where unregister_fentry would fail now,
that'd be bug that we'd need to fix. We have WARN_ON_ONCE on tampoline
unlink fail.
The fix is meant for when this happens let's go with un-released
trampoline image rather than kernel crash.
jirka
next prev parent reply other threads:[~2026-04-25 20:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-24 15:39 [PATCH bpf 1/2] bpf: Do not release trampoline image in case off unregister error Jiri Olsa
2026-04-24 15:39 ` [PATCH bpf 2/2] bpf: Remove obsolete WARN_ON call Jiri Olsa
2026-04-24 15:51 ` Song Liu
2026-04-24 15:50 ` [PATCH bpf 1/2] bpf: Do not release trampoline image in case off unregister error Song Liu
2026-04-25 20:40 ` Jiri Olsa [this message]
2026-04-24 16:22 ` bot+bpf-ci
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