[PATCH 4.4 19/27] ubifs: Check for name being NULL while mounting

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Richard Weinberger <richard@xxxxxx>

commit 37f31b6ca4311b94d985fb398a72e5399ad57925 upstream.

The requested device name can be NULL or an empty string.
Check for that and refuse to continue. UBIFS has to do this manually
since we cannot use mount_bdev(), which checks for this condition.

Fixes: 1e51764a3c2ac ("UBIFS: add new flash file system")
Reported-by: syzbot+38bd0f7865e5c6379280@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/ubifs/super.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1918,6 +1918,9 @@ static struct ubi_volume_desc *open_ubi(
 	int dev, vol;
 	char *endptr;
 
+	if (!name || !*name)
+		return ERR_PTR(-EINVAL);
+
 	/* First, try to open using the device node path method */
 	ubi = ubi_open_volume_path(name, mode);
 	if (!IS_ERR(ubi))