perf sort: Check return value of strdup()

When setup_sorting() is called, 'str' is passed to strtok_r() but it's
not checked to have a valid pointer.  As strtok_r() accepts NULL pointer
on a first argument and use the third argument in that case, it can
cause a trouble since our third argument, tmp, is not initialized.

Signed-off-by: Namhyung Kim <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: Namhyung Kim

tools/perf/util/sort.c

@@ -570,6 +570,11 @@ int setup_sorting(void)
 	char *tmp, *tok, *str = strdup(sort_order);
 	int ret = 0;
 
+	if (str == NULL) {
+		error("Not enough memory to setup sort keys");
+		return -ENOMEM;
+	}
+
 	for (tok = strtok_r(str, ", ", &tmp);
 			tok; tok = strtok_r(NULL, ", ", &tmp)) {
 		ret = sort_dimension__add(tok);