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@xxxxxxxxxxxxxxx # v5.7.x: 0fa8263367db: ceph: fix endianness bug when handling MDS session feature bits Fixes: 0fa8263367db (ceph: fix endianness bug when handling MDS session feature bits) URL: https://tracker.ceph.com/issues/46823 Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> --- fs/ceph/mds_client.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 1095802ad9bd..4a26862d7667 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -3358,8 +3358,10 @@ static void handle_session(struct ceph_mds_session *session, 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); -- 2.26.2
