On 09/11/2022 18:03, Ilya Dryomov wrote:

On Wed, Nov 9, 2022 at 4:00 AM xiubli@redhat.com wrote:

...

From: Xiubo Li xiubli@redhat.com

When decoding the snaps fails it maybe leaving the 'first_realm' and 'realm' pointing to the same snaprealm memory. And then it'll put it twice and could cause random use-after-free, BUG_ON, etc issues.

Cc: stable@vger.kernel.org URL: https://tracker.ceph.com/issues/57686 Signed-off-by: Xiubo Li xiubli@redhat.com

---

Changed in V4:

• remove initilizing of 'realm'.

  fs/ceph/snap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 9bceed2ebda3..c1c452afa84d 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -764,7 +764,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc, struct ceph_mds_snap_realm *ri; /* encoded */ __le64 *snaps; /* encoded */ __le64 *prior_parent_snaps; /* encoded */

•   struct ceph_snap_realm *realm = NULL;
  

•   struct ceph_snap_realm *realm;
     struct ceph_snap_realm *first_realm = NULL;
     struct ceph_snap_realm *realm_to_rebuild = NULL;
     int rebuild_snapcs;
  

@@ -775,6 +775,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,

     dout("%s deletion=%d\n", __func__, deletion);

more:

•   realm = NULL;
     rebuild_snapcs = 0;
     ceph_decode_need(&p, e, sizeof(*ri), bad);
     ri = p;
  

-- 2.31.1

Reviewed-by: Ilya Dryomov idryomov@gmail.com

Thanks very much Ilya!

Thanks,

             Ilya