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| author | Luis Henriques <lhenriques@suse.de> | 2020-11-12 10:45:12 +0000 |
|---|---|---|
| committer | Ilya Dryomov <idryomov@gmail.com> | 2020-12-14 23:21:47 +0100 |
| commit | e5cafce3ad0f8652d6849314d951459c2bff7233 (patch) | |
| tree | 1c0471a9dc891b9db9a0171eda41432e66029468 /fs/ceph | |
| parent | 4a357f5069428afc7c48cb4bdc95c864b7a5c862 (diff) | |
| download | lwn-e5cafce3ad0f8652d6849314d951459c2bff7233.tar.gz lwn-e5cafce3ad0f8652d6849314d951459c2bff7233.zip | |
ceph: fix race in concurrent __ceph_remove_cap invocations
A NULL pointer dereference may occur in __ceph_remove_cap with some of the
callbacks used in ceph_iterate_session_caps, namely trim_caps_cb and
remove_session_caps_cb. Those callers hold the session->s_mutex, so they
are prevented from concurrent execution, but ceph_evict_inode does not.
Since the callers of this function hold the i_ceph_lock, the fix is simply
a matter of returning immediately if caps->ci is NULL.
Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/43272
Suggested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Luis Henriques <lhenriques@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs/ceph')
| -rw-r--r-- | fs/ceph/caps.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 1c4d72c5f236..255a512f1277 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1140,12 +1140,19 @@ void __ceph_remove_cap(struct ceph_cap *cap, bool queue_release) { struct ceph_mds_session *session = cap->session; struct ceph_inode_info *ci = cap->ci; - struct ceph_mds_client *mdsc = - ceph_sb_to_client(ci->vfs_inode.i_sb)->mdsc; + struct ceph_mds_client *mdsc; int removed = 0; + /* 'ci' being NULL means the remove have already occurred */ + if (!ci) { + dout("%s: cap inode is NULL\n", __func__); + return; + } + dout("__ceph_remove_cap %p from %p\n", cap, &ci->vfs_inode); + mdsc = ceph_inode_to_client(&ci->vfs_inode)->mdsc; + /* remove from inode's cap rbtree, and clear auth cap */ rb_erase(&cap->ci_node, &ci->i_caps); if (ci->i_auth_cap == cap) { |