tools/vm/page_owner_sort.c: add a security check

Add a security check after using malloc() to allocate memory.

Link: https://lkml.kernel.org/r/20220301151438.166118-2-yejiajian2018@email.szu.edu.cnSigned-off-by: Jiajian Ye <yejiajian2018@email.szu.edu.cn>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Yinan Zhang <zhangyinan2019@email.szu.edu.cn>
Cc: Yixuan Cao <caoyixuan2019@email.szu.edu.cn>
Cc: Zhenliang Wei <weizhenliang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/vm/page_owner_sort.c

@@ -217,7 +217,13 @@ static void add_list(char *buf, int len)
 		printf("max_size too small??\n");
 		exit(1);
 	}
+
 	list[list_size].txt = malloc(len+1);
+	if (!list[list_size].txt) {
+		printf("Out of memory\n");
+		exit(1);
+	}
+
 	list[list_size].len = len;
 	list[list_size].num = 1;
 	list[list_size].page_num = get_page_num(buf);