[PATCH 4.18 24/35] uio: fix wrong return value from uio_mmap()

[Greg Kroah-Hartman]

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

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

From: Hailong Liu <liu.hailong6@xxxxxxxxxx>

commit e7de2590f18a272e63732b9d519250d1b522b2c4 upstream.

uio_mmap has multiple fail paths to set return value to nonzero then
goto out. However, it always returns *0* from the *out* at end, and
this will mislead callers who check the return value of this function.

Fixes: 57c5f4df0a5a0ee ("uio: fix crash after the device is unregistered")
CC: Xiubo Li <xiubli@xxxxxxxxxx>
Signed-off-by: Hailong Liu <liu.hailong6@xxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jiang Biao <jiang.biao2@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/uio/uio.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -814,7 +814,7 @@ static int uio_mmap(struct file *filep,
 
 out:
 	mutex_unlock(&idev->info_lock);
-	return 0;
+	return ret;
 }
 
 static const struct file_operations uio_fops = {