[PATCH 22.5/77] block/loop: fix error return value in loop_add()

[Tejun Heo]

If queue or disk allocation fails, loop_add() returns @err, which is
cleared to zero by idr allocation by that point.  Reset @err to
-ENOMEM before the allocations so that we return -ENOMEM instead of 0
on alloc failure.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
Hey, guys.

I was going through the conversions one more time and noticed this
existing bug.  We're returning 0 on alloc failure.  It seems the worst
which can come out of this is userland misled to believe a loop device
has been created when in fact it failed.  This can be routed
separately but it probably is easier to route with other changes.

Thanks!

 drivers/block/loop.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1649,6 +1649,7 @@ static int loop_add(struct loop_device *
 	if (err < 0)
 		goto out_free_dev;
 
+	err = -ENOMEM;
 	lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
 	if (!lo->lo_queue)
 		goto out_free_dev;
--
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