From: Dave Chinner dchinner@redhat.com
[ Upstream commit 0c7273e494dd5121e20e160cb2f047a593ee14a8 ]
The background inode inactivation can attached dquots to inodes, but this can race with a foreground quotacheck failure that leads to disabling quotas and freeing the mp->m_quotainfo structure. The background inode inactivation then tries to allocate a quota, tries to dereference mp->m_quotainfo, and crashes like so:
XFS (loop1): Quotacheck: Unsuccessful (Error -5): Disabling quotas. xfs filesystem being mounted at /root/syzkaller.qCVHXV/0/file0 supports timestamps until 2038 (0x7fffffff) BUG: kernel NULL pointer dereference, address: 00000000000002a8 .... CPU: 0 PID: 161 Comm: kworker/0:4 Not tainted 6.2.0-c9c3395d5e3d #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Workqueue: xfs-inodegc/loop1 xfs_inodegc_worker RIP: 0010:xfs_dquot_alloc+0x95/0x1e0 .... Call Trace: <TASK> xfs_qm_dqread+0x46/0x440 xfs_qm_dqget_inode+0x154/0x500 xfs_qm_dqattach_one+0x142/0x3c0 xfs_qm_dqattach_locked+0x14a/0x170 xfs_qm_dqattach+0x52/0x80 xfs_inactive+0x186/0x340 xfs_inodegc_worker+0xd3/0x430 process_one_work+0x3b1/0x960 worker_thread+0x52/0x660 kthread+0x161/0x1a0 ret_from_fork+0x29/0x50 </TASK> ....
Prevent this race by flushing all the queued background inode inactivations pending before purging all the cached dquots when quotacheck fails.
Reported-by: Pengfei Xu pengfei.xu@intel.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 Signed-off-by: Leah Rumancik leah.rumancik@gmail.com Acked-by: Chandan Babu R chandanbabu@kernel.org --- fs/xfs/xfs_qm.c | 40 ++++++++++++++++++++++++++-------------- 1 file changed, 26 insertions(+), 14 deletions(-)
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c index ff53d40a2dae..f51960d7dcbd 100644 --- a/fs/xfs/xfs_qm.c +++ b/fs/xfs/xfs_qm.c @@ -1321,15 +1321,14 @@ xfs_qm_quotacheck(
error = xfs_iwalk_threaded(mp, 0, 0, xfs_qm_dqusage_adjust, 0, true, NULL); - if (error) { - /* - * The inode walk may have partially populated the dquot - * caches. We must purge them before disabling quota and - * tearing down the quotainfo, or else the dquots will leak. - */ - xfs_qm_dqpurge_all(mp); - goto error_return; - } + + /* + * On error, the inode walk may have partially populated the dquot + * caches. We must purge them before disabling quota and tearing down + * the quotainfo, or else the dquots will leak. + */ + if (error) + goto error_purge;
/* * We've made all the changes that we need to make incore. Flush them @@ -1363,10 +1362,8 @@ xfs_qm_quotacheck( * and turn quotaoff. The dquots won't be attached to any of the inodes * at this point (because we intentionally didn't in dqget_noattach). */ - if (error) { - xfs_qm_dqpurge_all(mp); - goto error_return; - } + if (error) + goto error_purge;
/* * If one type of quotas is off, then it will lose its @@ -1376,7 +1373,7 @@ xfs_qm_quotacheck( mp->m_qflags &= ~XFS_ALL_QUOTA_CHKD; mp->m_qflags |= flags;
- error_return: +error_return: xfs_buf_delwri_cancel(&buffer_list);
if (error) { @@ -1395,6 +1392,21 @@ xfs_qm_quotacheck( } else xfs_notice(mp, "Quotacheck: Done."); return error; + +error_purge: + /* + * On error, we may have inodes queued for inactivation. This may try + * to attach dquots to the inode before running cleanup operations on + * the inode and this can race with the xfs_qm_destroy_quotainfo() call + * below that frees mp->m_quotainfo. To avoid this race, flush all the + * pending inodegc operations before we purge the dquots from memory, + * ensuring that background inactivation is idle whilst we turn off + * quotas. + */ + xfs_inodegc_flush(mp); + xfs_qm_dqpurge_all(mp); + goto error_return; + }
/*