mtd: concat: Use kmemdup_array instead of kmemdup for multiple allocation

When we are allocating an array, using kmemdup_array() to take care about
multiplication and possible overflows.

Also it makes auditing the code easier.

Signed-off-by: Yan Zhen <yanzhen@vivo.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20240823110824.3895787-1-yanzhen@vivo.com

Author: Yan Zhen

drivers/mtd/mtdconcat.c

@@ -204,7 +204,7 @@ concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
 	}
 
 	/* make a copy of vecs */
-	vecs_copy = kmemdup(vecs, sizeof(struct kvec) * count, GFP_KERNEL);
+	vecs_copy = kmemdup_array(vecs, count, sizeof(struct kvec), GFP_KERNEL);
 	if (!vecs_copy)
 		return -ENOMEM;