perf auxtrace: Fix potential NULL pointer dereference

In the function auxtrace_parse_snapshot_options(), the callback pointer
"itr->parse_snapshot_options" can be NULL if it has not been set during
the AUX record initialization.  This can cause tool crashing if the
callback pointer "itr->parse_snapshot_options" is dereferenced without
performing NULL check.

Add a NULL check for the pointer "itr->parse_snapshot_options" before
invoke the callback.

Fixes: d20031bb63dd6dde ("perf tools: Add AUX area tracing Snapshot Mode")
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: http://lore.kernel.org/lkml/20210420151554.2031768-1-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index 5b6ccb90b39712916203d405019460caeac7812a..1b4091a3b508bf2babf2133d0e5e790cb7a6ba79 100644 (file)
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -634,7 +634,7 @@ int auxtrace_parse_snapshot_options(struct auxtrace_record *itr,
                break;
        }
 
-       if (itr)
+       if (itr && itr->parse_snapshot_options)
                return itr->parse_snapshot_options(itr, opts, str);
 
        pr_err("No AUX area tracing to snapshot\n");