[PATCH v1 05/11] perf trace: Smatch: Fix potential NULL pointer dereference

[Leo Yan]

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

  tools/perf/builtin-trace.c:1044
  thread_trace__new() error: we previously assumed 'ttrace' could be
  null (see line 1041).

tools/perf/builtin-trace.c
1037 static struct thread_trace *thread_trace__new(void)
1038 {
1039         struct thread_trace *ttrace =  zalloc(sizeof(struct thread_trace));
1040
1041         if (ttrace)
1042                 ttrace->files.max = -1;
1043
1044         ttrace->syscall_stats = intlist__new(NULL);
             ^^^^^^^^
1045
1046         return ttrace;
1047 }

This patch directly returns NULL when fail to allocate memory for
ttrace; this can avoid potential NULL pointer dereference.

Signed-off-by: Leo Yan <leo....@linaro.org>
---
 tools/perf/builtin-trace.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index f3532b081b31..874d78890c60 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1038,9 +1038,10 @@ static struct thread_trace *thread_trace__new(void)
 {
        struct thread_trace *ttrace =  zalloc(sizeof(struct thread_trace));
 
-       if (ttrace)
-               ttrace->files.max = -1;
+       if (ttrace == NULL)
+               return NULL;
 
+       ttrace->files.max = -1;
        ttrace->syscall_stats = intlist__new(NULL);
 
        return ttrace;
-- 
2.17.1