Re: [PATCH 1/3] nbd: del_gendisk after we cleanup the queue
On Fri, Apr 13, 2018 at 04:16:18PM +0000, Bart Van Assche wrote:
> On Fri, 2018-04-13 at 12:03 -0400, Josef Bacik wrote:
> > This fixes a use after free bug, we need to do the del_gendisk after we
> > cleanup the queue on the device.
>
> Hello Josef,
>
> Which use-after-free bug does this patch fix? Are you aware that most block
> drivers call blk_cleanup_queue() before calling del_gendisk()? Why do you
> think that the nbd driver should use the opposite order?
>
I'm confused, that's what this patch does. Before I had del_gendisk() first and
then the blk_cleanup_queue(), which was bugging out when I was testing stuff
with a null pointer deref whenever I rmmod'ed the nbd. Swapping it to the way
everybody else did it fixed the problem. Thanks,
Josef
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