From: Jeff Layton jlayton@kernel.org
commit 02e37571f9e79022498fd0525c073b07e9d9ac69 upstream.
Most session messages contain a feature mask, but the MDS will routinely send a REJECT message with one that is zero-length.
Commit 0fa8263367db ("ceph: fix endianness bug when handling MDS session feature bits") fixed the decoding of the feature mask, but failed to account for the MDS sending a zero-length feature mask. This causes REJECT message decoding to fail.
Skip trying to decode a feature mask if the word count is zero.
Cc: stable@vger.kernel.org URL: https://tracker.ceph.com/issues/46823 Fixes: 0fa8263367db ("ceph: fix endianness bug when handling MDS session feature bits") Signed-off-by: Jeff Layton jlayton@kernel.org Reviewed-by: Ilya Dryomov idryomov@gmail.com Tested-by: Patrick Donnelly pdonnell@redhat.com Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/ceph/mds_client.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -3091,8 +3091,10 @@ static void handle_session(struct ceph_m goto bad; /* version >= 3, feature bits */ ceph_decode_32_safe(&p, end, len, bad); - ceph_decode_64_safe(&p, end, features, bad); - p += len - sizeof(features); + if (len) { + ceph_decode_64_safe(&p, end, features, bad); + p += len - sizeof(features); + } }
mutex_lock(&mdsc->mutex);