Re: [PATCH 2/8] block/export: Fix null pointer dereference in error path

[Eric Blake]

On Fri, May 12, 2023 at 11:16:03AM -0500, Eric Blake wrote:
> 
> 
> On Wed, May 10, 2023 at 10:35:55PM +0200, Kevin Wolf wrote:
> > 
> > There are some error paths in blk_exp_add() that jump to 'fail:' before
> > 'exp' is even created. So we can't just unconditionally access exp->blk.
> > 
> > Add a NULL check, and switch from exp->blk to blk, which is available
> > earlier, just to be extra sure that we really cover all cases where
> > BlockDevOps could have been set for it (in practice, this only happens
> > in drv->create() today, so this part of the change isn't strictly
> > necessary).
> > 
> > Fixes: de79b52604e43fdeba6cee4f5af600b62169f2d2
> 
> Sorry for missing that on my first review, and this does look better.
> 
> I'm assuming you plan to take this in with the rest of the series
> through your tree, but let me know if I should push it faster through
> the NBD tree.

Because iotest:
./check 307 -nbd

fails without this patch but passes with it,

Tested-by: Eric Blake <eblake@redhat.com>

[and I should really remember to run more iotests than just the subset
run by 'make check' when preparing a pull request...]

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org