bpf: fix corruption on concurrent perf_event_output calls

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[ Upstream commit 283ca526a9 ]

When tracing and networking programs are both attached in the
system and both use event-output helpers that eventually call
into perf_event_output(), then we could end up in a situation
where the tracing attached program runs in user context while
a cls_bpf program is triggered on that same CPU out of softirq
context.

Since both rely on the same per-cpu perf_sample_data, we could
potentially corrupt it. This can only ever happen in a combination
of the two types; all tracing programs use a bpf_prog_active
counter to bail out in case a program is already running on
that CPU out of a different context. XDP and cls_bpf programs
by themselves don't have this issue as they run in the same
context only. Therefore, split both perf_sample_data so they
cannot be accessed from each other.

Fixes: 20b9d7ac48 ("bpf: avoid excessive stack usage for perf_sample_data")
Reported-by: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Song Liu <songliubraving@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Daniel Borkmann 2017-12-22 16:23:00 +01:00 • committed by Greg Kroah-Hartman

parent 2b3ea8ceb2

commit a23244e884

1 changed files with 12 additions and 7 deletions

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kernel/trace/bpf_trace.c

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