From: Xiubo Li xiubli@redhat.com
commit 7acae6183cf37c48b8da48bbbdb78820fb3913f3 upstream.
The request will be inserted into the ci->i_unsafe_dirops before assigning the req->r_session, so it's possible that we will hit NULL pointer dereference bug here.
Cc: stable@vger.kernel.org URL: https://tracker.ceph.com/issues/55327 Signed-off-by: Xiubo Li xiubli@redhat.com Reviewed-by: Jeff Layton jlayton@kernel.org Tested-by: Aaron Tomlin atomlin@redhat.com Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ceph/caps.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -2266,6 +2266,8 @@ retry: list_for_each_entry(req, &ci->i_unsafe_dirops, r_unsafe_dir_item) { s = req->r_session; + if (!s) + continue; if (unlikely(s->s_mds >= max_sessions)) { spin_unlock(&ci->i_unsafe_lock); for (i = 0; i < max_sessions; i++) { @@ -2286,6 +2288,8 @@ retry: list_for_each_entry(req, &ci->i_unsafe_iops, r_unsafe_target_item) { s = req->r_session; + if (!s) + continue; if (unlikely(s->s_mds >= max_sessions)) { spin_unlock(&ci->i_unsafe_lock); for (i = 0; i < max_sessions; i++) {