[tip:perf/core] perf record: Fix failed memory allocation for get_cpuid_str

[tip-bot for Thomas Richter <tipbot@zytor.com>]

Commit-ID:  81fccd6ca507d3b2012eaf1edeb9b1dbf4bd22db
Gitweb:     https://git.kernel.org/tip/81fccd6ca507d3b2012eaf1edeb9b1dbf4bd22db
Author:     Thomas Richter <tmricht@linux.vnet.ibm.com>
AuthorDate: Wed, 17 Jan 2018 14:16:11 +0100
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 17 Jan 2018 10:31:25 -0300

perf record: Fix failed memory allocation for get_cpuid_str

In x86 architecture dependend part function get_cpuid_str() mallocs a
128 byte buffer, but does not check if the memory allocation succeeded
or not.

When the memory allocation fails, function __get_cpuid() is called with
first parameter being a NULL pointer.  However this function references
its first parameter and operates on a NULL pointer which might cause
core dumps.

Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/20180117131611.34319-1-tmricht@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/arch/x86/util/header.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/arch/x86/util/header.c b/tools/perf/arch/x86/util/header.c
index b626d2b..fb0d71a 100644
--- a/tools/perf/arch/x86/util/header.c
+++ b/tools/perf/arch/x86/util/header.c
@@ -70,7 +70,7 @@ get_cpuid_str(struct perf_pmu *pmu __maybe_unused)
 {
 	char *buf = malloc(128);
 
-	if (__get_cpuid(buf, 128, "%s-%u-%X$") < 0) {
+	if (buf && __get_cpuid(buf, 128, "%s-%u-%X$") < 0) {
 		free(buf);
 		return NULL;
 	}