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authorLuis Henriques <lhenriques@suse.de>2020-11-12 10:45:12 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-12-29 13:42:44 +0100
commit89374c84459e05522fe2058b8235f7c21ec0ba84 (patch)
treeae56448c8af777f22e0e95f3802527b3f748ba3f /fs
parentf4ce2117019fc4d80aef8cb8c159dd49330118a2 (diff)
ceph: fix race in concurrent __ceph_remove_cap invocations
commit e5cafce3ad0f8652d6849314d951459c2bff7233 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-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 49e693232916..9d74cd37b395 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -920,12 +920,19 @@ 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)