Commit 02e37571 authored Aug 04, 2020 by Jeff Layton Committed by Ilya Dryomov Aug 05, 2020

ceph: handle zero-length feature mask in session messages

Most session messages contain a feature mask, but the MDS will
routinely send a REJECT message with one that is zero-length.

Commit 0fa82633 ("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: 0fa82633 ("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>

parent 224c7b67

fs/ceph/mds_client.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -3358,9 +3358,11 @@ static void handle_session(struct ceph_mds_session *session,
		goto bad;
		/* version >= 3, feature bits */
		ceph_decode_32_safe(&p, end, len, bad);
		if (len) {
		ceph_decode_64_safe(&p, end, features, bad);
		p += len - sizeof(features);
		}
		}

		mutex_lock(&mdsc->mutex);
		if (op == CEPH_SESSION_CLOSE) {

Admin message