Messages in this thread | | | Date | Wed, 22 Aug 2018 18:12:28 +0200 | From | Jan Kara <> | Subject | Re: [PATCH 0/2] fs/quota: Fix potential spectre v1 gadgets |
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On Tue 31-07-18 13:43:44, Josh Poimboeuf wrote: > On Tue, Jul 31, 2018 at 01:37:29AM +0000, Jeremy Cline wrote: > > Hi folks, > > > > This series unifies XQM_MAXQUOTAS with MAXQUOTAS, which were both being > > used to perform bounds checks on arrays, and then sanitizes 'type' so it > > can't be used in speculative out-of-bounds array access. > > > > Jeremy Cline (2): > > fs/quota: Replace XQM_MAXQUOTAS usage with MAXQUOTAS > > fs/quota: Fix spectre gadget in do_quotactl > > > > fs/quota/quota.c | 14 +++++++------- > > include/linux/quota.h | 8 +------- > > include/uapi/linux/dqblk_xfs.h | 5 ----- > > 3 files changed, 8 insertions(+), 19 deletions(-) > > Looks good to me, though this might hinge on the discussion with > Andreas: > > https://lkml.kernel.org/r/E3E7B6AF-3819-4998-9B12-DACB4EBC14F1@dilger.ca
Actually, XQM_MAXQUOTAS is a different kind of beast than EXT4_MAXQUOTAS and friends. XQM_MAXQUOTAS is maximum allowed type number for some quotactl(8) syscall commands. After quite some effort we have unified the interfaces for all quotactl commands so they support the same set of quota types and we don't really plan for these two diverge in the future again. So the cleanup makes sense.
OTOH EXT4_MAXQUOTAS defines how many quota types ext4 filesystem supports and that definitely needs to stay a separate constant from the number of quota types generic infrastructure supports... So here I agree with Andreas.
Honza -- Jan Kara <jack@suse.com> SUSE Labs, CR
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