diff --git a/mm/util.c b/mm/util.c
index 744b4d7e3fae..2581d687df87 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -194,7 +194,7 @@ void *memdup_user(const void __user *src, size_t len)
 {
 	void *p;
 
-	p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
+	p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN | __GFP_ZERO);
 	if (!p)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index f9544fda38e9..8318f6a21b3d 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -730,7 +730,7 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 			    struct btrfs_ioctl_dev_replace_args *args)
 {
-	int ret;
+	int ret, len;
 
 	switch (args->start.cont_reading_from_srcdev_mode) {
 	case BTRFS_IOCTL_DEV_REPLACE_CONT_READING_FROM_SRCDEV_MODE_ALWAYS:
@@ -740,8 +740,11 @@ int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 		return -EINVAL;
 	}
 
+	len = strnlen(args->start.tgtdev_name, BTRFS_DEVICE_PATH_NAME_MAX + 1);
+	printk("l: %d, >%s<, %s\n", len, args->start.tgtdev_name, __func__);
 	if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
-	    args->start.tgtdev_name[0] == '\0')
+	    args->start.tgtdev_name[0] == '\0' ||
+	    len == BTRFS_DEVICE_PATH_NAME_MAX + 1)
 		return -EINVAL;
 
 	ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,