Re: [PATCH 1/2] ocfs2: bound namelen in dlm_migrate_request_handler

[Joseph Qi <joseph.qi@linux.alibaba.com>]

On 6/29/26 1:01 PM, Bryam Vargas via B4 Relay wrote:
> From: Bryam Vargas <hexlabsecurity@proton.me>
> 
> A node receiving a DLM_MIGRATE_REQUEST message trusts the peer-supplied
> name length (migrate->namelen) without bounding it.  dlm_init_mle() then
> copies that many bytes into the fixed DLM_LOCKID_NAME_MAX-byte mname[]
> array of an o2dlm_mle slab object, so a malformed message from a cluster
> peer overflows the slab object by up to ~215 bytes: a heap out-of-bounds
> write of attacker-controlled data, reachable by any node in the domain.
> 
> Reject an oversized name, the way dlm_master_request_handler() and the
> other o2dlm receive handlers already do; the migration handler omits the
> check entirely.  Conforming messages are unaffected.
> 
> Fixes: 6714d8e86bf4 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem")
> Cc: stable@vger.kernel.org
> Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>

Looks fine.
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
> ---
>  fs/ocfs2/dlm/dlmmaster.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
> index 93eff38fdadd..bd7623cc6e77 100644
> --- a/fs/ocfs2/dlm/dlmmaster.c
> +++ b/fs/ocfs2/dlm/dlmmaster.c
> @@ -3100,6 +3100,12 @@ int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
>  
>  	name = migrate->name;
>  	namelen = migrate->namelen;
> +	if (namelen > DLM_LOCKID_NAME_MAX) {
> +		mlog(ML_ERROR, "%s: invalid name length %u in migrate request\n",
> +		     dlm->name, namelen);
> +		ret = -EINVAL;
> +		goto leave;
> +	}
>  	hash = dlm_lockid_hash(name, namelen);
>  
>  	/* preallocate.. if this fails, abort */
>