Re: [PATCH] xfs: fix missing ILOCK unlock when xfs_setattr_nonsize fails due to EDQUOT

[Salvatore Bonaccorso <carnil@debian.org>]

Hi,

On Fri, Aug 23, 2019 at 09:26:12PM +0200, Salvatore Bonaccorso wrote:
> Hi Linus,
> 
> On Fri, Aug 23, 2019 at 09:28:42AM -0700, Linus Torvalds wrote:
> > On Thu, Aug 22, 2019 at 8:55 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
> > >
> > > ...which is clearly caused by xfs_setattr_nonsize failing to unlock the
> > > ILOCK after the xfs_qm_vop_chown_reserve call fails.  Add the missing
> > > unlock.
> > 
> > Thanks for the quick fix.
> > 
> > I assume there's no real embargo on this, and we can just add it asap
> > to the xfs tree and mark it for stable, rather than do anything
> > outside the usual development path?
> > 
> > The security list rules do allow for a 5-working-day delay, but this
> > being "just" a local DoS thing I expect nobody really will argue for
> > it.
> > 
> > Anybody?
> 
> Agreed, there is no real embargo on this, it is public anyway on the
> xfs list and actually we just wanted to be on the safe side by asking
> or bringing it to security@k.o.
> 
> Thanks for the quick fix.

Not changing my mind on the above, given the fixing commit is public.

But thinking a bit more on it, I guess this should not considered
local DoS only. If the filesystem is exosed then a remote user might
trigger it serverside.

The issue could be reproduced on a NFS exported XFS as well. Just
export the filesystem rw to another host via NFS and mount it there. A
local user on the client could then trigger the issue on the server as
well.

Regards,
Salvatore