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 <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Hendrik Brueckner <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: Thomas Richter

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;
 	}