selftests: ublk: fix ublk_find_tgt()

Bounds check for iterator variable `i` is missed, so add it and fix
ublk_find_tgt().

Cc: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250412023035.2649275-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Ming Lei

tools/testing/selftests/ublk/kublk.c

@@ -14,13 +14,12 @@ static const struct ublk_tgt_ops *tgt_ops_list[] = {
 
 static const struct ublk_tgt_ops *ublk_find_tgt(const char *name)
 {
-	const struct ublk_tgt_ops *ops;
 	int i;
 
 	if (name == NULL)
 		return NULL;
 
-	for (i = 0; sizeof(tgt_ops_list) / sizeof(ops); i++)
+	for (i = 0; i < ARRAY_SIZE(tgt_ops_list); i++)
 		if (strcmp(tgt_ops_list[i]->name, name) == 0)
 			return tgt_ops_list[i];
 	return NULL;

tools/testing/selftests/ublk/kublk.h

@@ -30,6 +30,8 @@
 #define min(a, b) ((a) < (b) ? (a) : (b))
 #endif
 
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))
+
 /****************** part 1: libublk ********************/
 
 #define CTRL_DEV		"/dev/ublk-control"