diff -puN fs/jffs2/acl.c~jffs2_acl_count-tests-0-on-unsigned fs/jffs2/acl.c
--- a/fs/jffs2/acl.c~jffs2_acl_count-tests-0-on-unsigned
+++ a/fs/jffs2/acl.c
@@ -38,12 +38,12 @@ static int jffs2_acl_count(size_t size)
 	size_t s;
 
 	size -= sizeof(struct jffs2_acl_header);
-	s = size - 4 * sizeof(struct jffs2_acl_entry_short);
-	if (s < 0) {
+	if (size < 4 * sizeof(struct jffs2_acl_entry_short)) {
 		if (size % sizeof(struct jffs2_acl_entry_short))
 			return -1;
 		return size / sizeof(struct jffs2_acl_entry_short);
 	} else {
+		s = size - 4 * sizeof(struct jffs2_acl_entry_short);
 		if (s % sizeof(struct jffs2_acl_entry))
 			return -1;
 		return s / sizeof(struct jffs2_acl_entry) + 4;