[PATCH 06/25] perf map: Fix potential NULL pointer dereference found by smatch tool

[Arnaldo Carvalho de Melo]

From: Leo Yan <leo.yan@xxxxxxxxxx>

Based on the following report from Smatch, fix the potential NULL
pointer dereference check.

  tools/perf/util/map.c:479
  map__fprintf_srccode() error: we previously assumed 'state' could be
  null (see line 466)

  tools/perf/util/map.c
  465         /* Avoid redundant printing */
  466         if (state &&
  467             state->srcfile &&
  468             !strcmp(state->srcfile, srcfile) &&
  469             state->line == line) {
  470                 free(srcfile);
  471                 return 0;
  472         }
  473
  474         srccode = find_sourceline(srcfile, line, &len);
  475         if (!srccode)
  476                 goto out_free_line;
  477
  478         ret = fprintf(fp, "|%-8d %.*s", line, len, srccode);
  479         state->srcfile = srcfile;
              ^^^^^^^
  480         state->line = line;
              ^^^^^^^

This patch validates 'state' pointer before access its elements.

Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
Cc: Alexios Zavras <alexios.zavras@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Changbin Du <changbin.du@xxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Eric Saint-Etienne <eric.saint.etienne@xxxxxxxxxx>
Cc: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: Suzuki Poulouse <suzuki.poulose@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Thomas Richter <tmricht@xxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Fixes: dd2e18e9ac20 ("perf tools: Support 'srccode' output")
Link: http://lkml.kernel.org/r/20190702103420.27540-8-leo.yan@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/map.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 6fce983c6115..5f87975d2562 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -476,8 +476,11 @@ int map__fprintf_srccode(struct map *map, u64 addr,
 		goto out_free_line;
 
 	ret = fprintf(fp, "|%-8d %.*s", line, len, srccode);
-	state->srcfile = srcfile;
-	state->line = line;
+
+	if (state) {
+		state->srcfile = srcfile;
+		state->line = line;
+	}
 	return ret;
 
 out_free_line:
-- 
2.21.0