diff --git a/[refs] b/[refs]
index 65e25a021586..55cb27386f0f 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1f7ba3311530993801d6877889efff0382bcd641
+refs/heads/master: 58c17b0e1b2278824aedc5d1201f6a43a38d6a48
diff --git a/trunk/drivers/block/rbd.c b/trunk/drivers/block/rbd.c
index 15bd3ecbcf34..a27167942a92 100644
--- a/trunk/drivers/block/rbd.c
+++ b/trunk/drivers/block/rbd.c
@@ -519,18 +519,19 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
 				 struct rbd_image_header_ondisk *ondisk)
 {
 	u32 snap_count;
+	size_t len;
 	size_t size;
 
 	memset(header, 0, sizeof (*header));
 
 	snap_count = le32_to_cpu(ondisk->snap_count);
 
-	size = sizeof (ondisk->object_prefix) + 1;
-	header->object_prefix = kmalloc(size, GFP_KERNEL);
+	len = strnlen(ondisk->object_prefix, sizeof (ondisk->object_prefix));
+	header->object_prefix = kmalloc(len + 1, GFP_KERNEL);
 	if (!header->object_prefix)
 		return -ENOMEM;
-	memcpy(header->object_prefix, ondisk->object_prefix, size - 1);
-	header->object_prefix[size - 1] = '\0';
+	memcpy(header->object_prefix, ondisk->object_prefix, len);
+	header->object_prefix[len] = '\0';
 
 	if (snap_count) {
 		header->snap_names_len = le64_to_cpu(ondisk->snap_names_len);