diff options
| author | Dave Chinner <dchinner@redhat.com> | 2022-12-08 08:29:22 -0800 |
|---|---|---|
| committer | Darrick J. Wong <djwong@kernel.org> | 2022-12-08 08:29:58 -0800 |
| commit | 52f31ed228212ba572c44e15e818a3a5c74122c0 (patch) | |
| tree | 969841c970dafd1e4dae2457c4d5a3dc4c88a839 /fs/xfs | |
| parent | 1f5619ed881081be300db61da552ffae7163bb72 (diff) | |
xfs: dquot shrinker doesn't check for XFS_DQFLAG_FREEING
Resulting in a UAF if the shrinker races with some other dquot
freeing mechanism that sets XFS_DQFLAG_FREEING before the dquot is
removed from the LRU. This can occur if a dquot purge races with
drop_caches.
Reported-by: syzbot+912776840162c13db1a3@syzkaller.appspotmail.com
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/xfs_qm.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c index 18bb4ec4d7c9..ff53d40a2dae 100644 --- a/fs/xfs/xfs_qm.c +++ b/fs/xfs/xfs_qm.c @@ -423,6 +423,14 @@ xfs_qm_dquot_isolate( goto out_miss_busy; /* + * If something else is freeing this dquot and hasn't yet removed it + * from the LRU, leave it for the freeing task to complete the freeing + * process rather than risk it being free from under us here. + */ + if (dqp->q_flags & XFS_DQFLAG_FREEING) + goto out_miss_unlock; + + /* * This dquot has acquired a reference in the meantime remove it from * the freelist and try again. */ @@ -441,10 +449,8 @@ xfs_qm_dquot_isolate( * skip it so there is time for the IO to complete before we try to * reclaim it again on the next LRU pass. */ - if (!xfs_dqflock_nowait(dqp)) { - xfs_dqunlock(dqp); - goto out_miss_busy; - } + if (!xfs_dqflock_nowait(dqp)) + goto out_miss_unlock; if (XFS_DQ_IS_DIRTY(dqp)) { struct xfs_buf *bp = NULL; @@ -478,6 +484,8 @@ xfs_qm_dquot_isolate( XFS_STATS_INC(dqp->q_mount, xs_qm_dqreclaims); return LRU_REMOVED; +out_miss_unlock: + xfs_dqunlock(dqp); out_miss_busy: trace_xfs_dqreclaim_busy(dqp); XFS_STATS_INC(dqp->q_mount, xs_qm_dqreclaim_misses); |