On 07/11/2022 23:21, Ilya Dryomov wrote:
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>
Yeah, makes sense.
I will fix this.
Thanks Ilya!
Thanks,
Ilya
