ceph: clear inode pointer when snap realm gets dropped by its inode

commit d95e674c01cfb5461e8b9fdeebf6d878c9b80b2f upstream.

snap realm and corresponding inode have pointers to each other.
The two pointer should get clear at the same time. Otherwise,
snap realm's pointer may reference freed inode.

Cc: stable@vger.kernel.org # 4.17+
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Luis Henriques <lhenriques@suse.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index a58666a3f8dd0c7083744c17a65bf3d12a795e2e..08aaf580fa1c97d3d5e02e391370c54642e49898 100644 (file)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1032,6 +1032,8 @@ static void drop_inode_snap_realm(struct ceph_inode_info *ci)
        list_del_init(&ci->i_snap_realm_item);
        ci->i_snap_realm_counter++;
        ci->i_snap_realm = NULL;
+       if (realm->ino == ci->i_vino.ino)
+               realm->inode = NULL;
        spin_unlock(&realm->inodes_with_caps_lock);
        ceph_put_snap_realm(ceph_sb_to_client(ci->vfs_inode.i_sb)->mdsc,
                            realm);