Re: [PATCH v2] migration/rdma: Fix cm_event used before being initialized

[Dr. David Alan Gilbert]

* Li Zhijian (lizhijian@cn.fujitsu.com) wrote:
> A segmentation fault was triggered when i try to abort a postcopy + rdma
> migration.
> 
> since rdma_ack_cm_event releases a uninitialized cm_event in these case.
> 
> like below:
> 2496     ret = rdma_get_cm_event(rdma->channel, &cm_event);
> 2497     if (ret) {
> 2498         perror("rdma_get_cm_event after rdma_connect");
> 2499         ERROR(errp, "connecting to destination!");
> 2500         rdma_ack_cm_event(cm_event); <<<< cause segmentation fault
> 2501         goto err_rdma_source_connect;
> 2502     }
> 
> Refer to the rdma_get_cm_event() code, cm_event will be
> updated/changed only if rdma_get_cm_event() returns 0. So it's okey to
> remove the ack in error patch.
> 
> Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>

Thanks!


Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
> V2: remove ack from the error patch (Dave)
> ---
>  migration/rdma.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/migration/rdma.c b/migration/rdma.c
> index 00eac34232..41726cc74a 100644
> --- a/migration/rdma.c
> +++ b/migration/rdma.c
> @@ -2497,7 +2497,6 @@ static int qemu_rdma_connect(RDMAContext *rdma, Error 
> **errp)
>      if (ret) {
>          perror("rdma_get_cm_event after rdma_connect");
>          ERROR(errp, "connecting to destination!");
> -        rdma_ack_cm_event(cm_event);
>          goto err_rdma_source_connect;
>      }
>  
> -- 
> 2.30.2
> 
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK