Re: [PATCH v3] ceph: avoid putting the realm twice when decoding snaps fails

[Xiubo Li <xiubli@redhat.com>]

On 08/11/2022 23:10, Ilya Dryomov wrote:
> On Tue, Nov 8, 2022 at 2:46 PM <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>
>> ---
>>   fs/ceph/snap.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
>> index 9bceed2ebda3..f5b0fa1ff705 100644
>> --- a/fs/ceph/snap.c
>> +++ b/fs/ceph/snap.c
>> @@ -775,6 +775,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
>>
>>          dout("%s deletion=%d\n", __func__, deletion);
>>   more:
>> +       realm = NULL;
> Nit: realm doesn't need to be initialized anymore, I would drop that.

I noticed that. Sure will remove that.

Thanks!

- Xiubo

> Thanks,
>
>                  Ilya
>