[tip:perf/urgent] perf tools: Check for null when copying nsinfo.

[tip-bot for Benno Evers]

Commit-ID:  3f4417d693b43fa240ac8bde4487f67745ca23d8
Gitweb:     https://git.kernel.org/tip/3f4417d693b43fa240ac8bde4487f67745ca23d8
Author:     Benno Evers <bevers@xxxxxxxxxxxxxx>
AuthorDate: Fri, 10 Aug 2018 15:36:13 +0200
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 13 Aug 2018 15:39:09 -0300

perf tools: Check for null when copying nsinfo.

The argument to nsinfo__copy() was assumed to be valid, but some code paths
exist that will lead to NULL being passed.

In particular, running 'perf script -D' on a perf.data file containing an
PERF_RECORD_MMAP event associating the '[vdso]' dso with pid 0 earlier in
the event stream will lead to a segfault.

Since all calling code is already checking for a non-null return value,
just return NULL for this case as well.

Signed-off-by: Benno Evers <bevers@xxxxxxxxxxxxxx>
Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Krister Johansen <kjlx@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20180810133614.9925-1-bevers@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/namespaces.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c
index 5be021701f34..cf8bd123cf73 100644
--- a/tools/perf/util/namespaces.c
+++ b/tools/perf/util/namespaces.c
@@ -139,6 +139,9 @@ struct nsinfo *nsinfo__copy(struct nsinfo *nsi)
 {
 	struct nsinfo *nnsi;
 
+	if (nsi == NULL)
+		return NULL;
+
 	nnsi = calloc(1, sizeof(*nnsi));
 	if (nnsi != NULL) {
 		nnsi->pid = nsi->pid;