diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index f9544fda38e9..31218d3aebe8 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -741,7 +741,8 @@ int btrfs_dev_replace_by_ioctl(struct btrfs_fs_info *fs_info,
 	}
 
 	if ((args->start.srcdevid == 0 && args->start.srcdev_name[0] == '\0') ||
-	    args->start.tgtdev_name[0] == '\0')
+	    args->start.tgtdev_name[0] == '\0' ||
+	    args->start.tgtdev_name[0] == 0)
 		return -EINVAL;
 
 	ret = btrfs_dev_replace_start(fs_info, args->start.tgtdev_name,
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4e50b62db2a8..20822e62f8b5 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3283,7 +3283,7 @@ static long btrfs_ioctl_dev_replace(struct btrfs_fs_info *fs_info,
 		return -EINVAL;
 	}
 
-	p = memdup_user(arg, sizeof(*p));
+	p = memdup_user(arg, 17);
 	if (IS_ERR(p))
 		return PTR_ERR(p);
 
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);