Re: [PATCH] ceph: fix incorrectly decoding the mdsmap bug

[Jeff Layton <jlayton@kernel.org>]

On Fri, 2021-11-05 at 17:34 +0800, xiubli@redhat.com wrote:
> From: Xiubo Li <xiubli@redhat.com>
> 
> When decreasing the 'max_mds' in the cephfs cluster, when the extra
> MDS or MDSes are not removed yet, the mdsmap may only decreased the
> 'max_mds' but still having the that or those MDSes 'in' or in the
> export targets list.
> 
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
>  fs/ceph/mdsmap.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c
> index 61d67cbcb367..30387733765d 100644
> --- a/fs/ceph/mdsmap.c
> +++ b/fs/ceph/mdsmap.c
> @@ -263,10 +263,6 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2)
>  				goto nomem;
>  			for (j = 0; j < num_export_targets; j++) {
>  				target = ceph_decode_32(&pexport_targets);
> -				if (target >= m->possible_max_rank) {
> -					err = -EIO;
> -					goto corrupt;
> -				}
>  				info->export_targets[j] = target;
>  			}
>  		} else {

Thanks Xiubo, looks good. Given the severity when mdsmap decoding fails,
I think we should probably mark this for stable too. Let me know if you
have any objections.
-- 
Jeff Layton <jlayton@kernel.org>