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

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 68e5cdd..1fcd123 100644 (file)
--- 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;