[PATCH 2/5] xfs: check dquot resource timers

Darrick J. Wong
2023-11-24T23:56:18Z

From: Darrick J. Wong <djwong@kernel.org>

For each dquot resource, ensure either (a) the resource usage is over
the soft limit and there is a nonzero timer; or (b) usage is at or under
the soft limit and the timer is unset. (a) is redundant with the dquot
buffer verifier, but (b) isn't checked anywhere.

Found by fuzzing xfs/426 and noticing that diskdq.btimer = add didn't
trip any kind of warning for having a timer set even with no limits.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/scrub/quota.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/fs/xfs/scrub/quota.c b/fs/xfs/scrub/quota.c
index 59350cd7a325b..49835d2840b4a 100644
--- a/fs/xfs/scrub/quota.c
+++ b/fs/xfs/scrub/quota.c
@@ -117,6 +117,23 @@ xchk_quota_item_bmap(
return 0;
}

+/* Complain if a quota timer is incorrectly set. */
+static inline void
+xchk_quota_item_timer(
+ struct xfs_scrub *sc,
+ xfs_fileoff_t offset,
+ const struct xfs_dquot_res *res)
+{
+ if ((res->softlimit && res->count > res->softlimit) ||
+ (res->hardlimit && res->count > res->hardlimit)) {
+ if (!res->timer)
+ xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
+ } else {
+ if (res->timer)
+ xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
+ }
+}
+
/* Scrub the fields in an individual quota item. */
STATIC int
xchk_quota_item(
@@ -224,6 +241,10 @@ xchk_quota_item(
dq->q_rtb.count > dq->q_rtb.hardlimit)
xchk_fblock_set_warning(sc, XFS_DATA_FORK, offset);

+ xchk_quota_item_timer(sc, offset, &dq->q_blk);
+ xchk_quota_item_timer(sc, offset, &dq->q_ino);
+ xchk_quota_item_timer(sc, offset, &dq->q_rtb);
+
out:
if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
return -ECANCELED;