On Mon, Nov 7, 2022 at 8:18 AM <xiubli@xxxxxxxxxx> wrote: > > From: Xiubo Li <xiubli@xxxxxxxxxx> > > 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@xxxxxxxxxxxxxxx > URL: https://tracker.ceph.com/issues/57686 > Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx> > --- > fs/ceph/snap.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c > index 9bceed2ebda3..baf17df05107 100644 > --- a/fs/ceph/snap.c > +++ b/fs/ceph/snap.c > @@ -849,10 +849,12 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc, > if (realm_to_rebuild && p >= e) > rebuild_snap_realms(realm_to_rebuild, &dirty_realms); > > - if (!first_realm) > + if (!first_realm) { > first_realm = realm; > - else > + realm = NULL; Hi Xiubo, I wonder why realm is cleared only in !first_realm branch? Can't the same issue occur with realm? first_realm is already set, ceph_put_snap_realm(realm) p < e, goto more decoding fails, goto bad realm is still set and not IS_ERR, ceph_put_snap_realm(realm) <realm is put twice> Thanks, Ilya
