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

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

[xiubli]

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;
 	rebuild_snapcs = 0;
 	ceph_decode_need(&p, e, sizeof(*ri), bad);
 	ri = p;
-- 
2.31.1

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

[Greg KH]

On Tue, Nov 08, 2022 at 09:46:33PM +0800, 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;
>  	rebuild_snapcs = 0;
>  	ceph_decode_need(&p, e, sizeof(*ri), bad);
>  	ri = p;
> -- 
> 2.31.1
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- This looks like a new version of a previously submitted patch, but you
  did not list below the --- line any changes from the previous version.
  Please read the section entitled "The canonical patch format" in the
  kernel file, Documentation/SubmittingPatches for what needs to be done
  here to properly describe this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

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

[Ilya Dryomov]

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.

Thanks,

                Ilya

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

[Xiubo Li]

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
>