diff options
| author | Xiubo Li <xiubli@redhat.com> | 2023-06-01 08:59:31 +0800 |
|---|---|---|
| committer | Ilya Dryomov <idryomov@gmail.com> | 2023-06-08 08:56:25 +0200 |
| commit | 409e873ea3c1fd3079909718bbeb06ac1ec7f38b (patch) | |
| tree | 4e7617c7a96cb654958715fdee3a6f5f315fc75c /fs/ceph | |
| parent | 870611e4877eff1e8413c3fb92a585e45d5291f6 (diff) | |
ceph: fix use-after-free bug for inodes when flushing capsnaps
There is a race between capsnaps flush and removing the inode from
'mdsc->snap_flush_list' list:
== Thread A == == Thread B ==
ceph_queue_cap_snap()
-> allocate 'capsnapA'
->ihold('&ci->vfs_inode')
->add 'capsnapA' to 'ci->i_cap_snaps'
->add 'ci' to 'mdsc->snap_flush_list'
...
== Thread C ==
ceph_flush_snaps()
->__ceph_flush_snaps()
->__send_flush_snap()
handle_cap_flushsnap_ack()
->iput('&ci->vfs_inode')
this also will release 'ci'
...
== Thread D ==
ceph_handle_snap()
->flush_snaps()
->iterate 'mdsc->snap_flush_list'
->get the stale 'ci'
->remove 'ci' from ->ihold(&ci->vfs_inode) this
'mdsc->snap_flush_list' will WARNING
To fix this we will increase the inode's i_count ref when adding 'ci'
to the 'mdsc->snap_flush_list' list.
[ idryomov: need_put int -> bool ]
Cc: stable@vger.kernel.org
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2209299
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs/ceph')
| -rw-r--r-- | fs/ceph/caps.c | 6 | ||||
| -rw-r--r-- | fs/ceph/snap.c | 4 |
2 files changed, 9 insertions, 1 deletions
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 789be30d6ee2..2321e5ddb664 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1627,6 +1627,7 @@ void ceph_flush_snaps(struct ceph_inode_info *ci, struct inode *inode = &ci->netfs.inode; struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc; struct ceph_mds_session *session = NULL; + bool need_put = false; int mds; dout("ceph_flush_snaps %p\n", inode); @@ -1671,8 +1672,13 @@ out: ceph_put_mds_session(session); /* we flushed them all; remove this inode from the queue */ spin_lock(&mdsc->snap_flush_lock); + if (!list_empty(&ci->i_snap_flush_item)) + need_put = true; list_del_init(&ci->i_snap_flush_item); spin_unlock(&mdsc->snap_flush_lock); + + if (need_put) + iput(inode); } /* diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 0b236ebd989f..2e73ba62bd7a 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -693,8 +693,10 @@ int __ceph_finish_cap_snap(struct ceph_inode_info *ci, capsnap->size); spin_lock(&mdsc->snap_flush_lock); - if (list_empty(&ci->i_snap_flush_item)) + if (list_empty(&ci->i_snap_flush_item)) { + ihold(inode); list_add_tail(&ci->i_snap_flush_item, &mdsc->snap_flush_list); + } spin_unlock(&mdsc->snap_flush_lock); return 1; /* caller may want to ceph_flush_snaps */ } |