tools lib traceevent: Check return value of arg_to_str()

The arg_to_str() can fail so we should handle that case properly.

Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/1335157118-14658-12-git-send-email-namhyung.kim@lge.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/lib/traceevent/parse-filter.c

@@ -2026,11 +2026,13 @@ static char *exp_to_str(struct event_filter *filter, struct filter_arg *arg)
 	char *lstr;
 	char *rstr;
 	char *op;
-	char *str;
+	char *str = NULL;
 	int len;
 
 	lstr = arg_to_str(filter, arg->exp.left);
 	rstr = arg_to_str(filter, arg->exp.right);
+	if (!lstr || !rstr)
+		goto out;
 
 	switch (arg->exp.type) {
 	case FILTER_EXP_ADD:
@@ -2070,6 +2072,7 @@ static char *exp_to_str(struct event_filter *filter, struct filter_arg *arg)
 	len = strlen(op) + strlen(lstr) + strlen(rstr) + 4;
 	str = malloc_or_die(len);
 	snprintf(str, len, "%s %s %s", lstr, op, rstr);
+out:
 	free(lstr);
 	free(rstr);
 
@@ -2086,6 +2089,8 @@ static char *num_to_str(struct event_filter *filter, struct filter_arg *arg)
 
 	lstr = arg_to_str(filter, arg->num.left);
 	rstr = arg_to_str(filter, arg->num.right);
+	if (!lstr || !rstr)
+		goto out;
 
 	switch (arg->num.type) {
 	case FILTER_CMP_EQ:
@@ -2122,6 +2127,7 @@ static char *num_to_str(struct event_filter *filter, struct filter_arg *arg)
 		break;
 	}
 
+out:
 	free(lstr);
 	free(rstr);
 	return str;
@@ -2272,7 +2278,12 @@ int pevent_filter_compare(struct event_filter *filter1, struct event_filter *fil
 		/* The best way to compare complex filters is with strings */
 		str1 = arg_to_str(filter1, filter_type1->filter);
 		str2 = arg_to_str(filter2, filter_type2->filter);
-		result = strcmp(str1, str2) != 0;
+		if (str1 && str2)
+			result = strcmp(str1, str2) != 0;
+		else
+			/* bail out if allocation fails */
+			result = 1;
+
 		free(str1);
 		free(str2);
 		if (result)