[tip: perf/core] bpf: Check flags for branch stack in bpf_read_branch_records helper

["tip-bot2 for Jiri Olsa" <tip-bot2@linutronix.de>]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     cce6a2d7e0e494c453ad73e1e78bd50684f20cca
Gitweb:        https://git.kernel.org/tip/cce6a2d7e0e494c453ad73e1e78bd50684f20cca
Author:        Jiri Olsa <jolsa@kernel.org>
AuthorDate:    Tue, 27 Sep 2022 22:32:59 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 27 Sep 2022 22:50:25 +02:00

bpf: Check flags for branch stack in bpf_read_branch_records helper

Recent commit [1] changed branch stack data indication from
br_stack pointer to sample_flags in perf_sample_data struct.

We need to check sample_flags for PERF_SAMPLE_BRANCH_STACK
bit for valid branch stack data.

[1] a9a931e26668 ("perf: Use sample_flags for branch stack")

Fixes: a9a931e26668 ("perf: Use sample_flags for branch stack")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20220927203259.590950-1-jolsa@kernel.org
---
 kernel/trace/bpf_trace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 68e5cdd..1fcd123 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1507,6 +1507,9 @@ BPF_CALL_4(bpf_read_branch_records, struct bpf_perf_event_data_kern *, ctx,
 	if (unlikely(flags & ~BPF_F_GET_BRANCH_RECORDS_SIZE))
 		return -EINVAL;
 
+	if (unlikely(!(ctx->data->sample_flags & PERF_SAMPLE_BRANCH_STACK)))
+		return -ENOENT;
+
 	if (unlikely(!br_stack))
 		return -ENOENT;