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| author | Luis Henriques <lhenriques@suse.de> | 2020-11-12 10:45:12 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-12-29 13:42:44 +0100 |
| commit | 89374c84459e05522fe2058b8235f7c21ec0ba84 (patch) | |
| tree | ae56448c8af777f22e0e95f3802527b3f748ba3f | |
| parent | f4ce2117019fc4d80aef8cb8c159dd49330118a2 (diff) | |
| download | linux-stable-89374c84459e05522fe2058b8235f7c21ec0ba84.tar.gz linux-stable-89374c84459e05522fe2058b8235f7c21ec0ba84.tar.bz2 linux-stable-89374c84459e05522fe2058b8235f7c21ec0ba84.zip | |
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>
| -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 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) |