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authorLuis Henriques <lhenriques@suse.de>2020-11-12 10:45:12 +0000
committerIlya Dryomov <idryomov@gmail.com>2020-12-14 23:21:47 +0100
commite5cafce3ad0f8652d6849314d951459c2bff7233 (patch)
tree1c0471a9dc891b9db9a0171eda41432e66029468 /fs/ceph/caps.c
parent4a357f5069428afc7c48cb4bdc95c864b7a5c862 (diff)
downloadlinux-e5cafce3ad0f8652d6849314d951459c2bff7233.tar.bz2
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/caps.c')
-rw-r--r--fs/ceph/caps.c11
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) {