Re: [dpdk-dev] [PATCH] vhost: fix crash if set vring num handling failed

[Ilya Maximets <i.maximets@samsung.com>]

Any thoughts on this?

Best regards, Ilya Maximets.

On 17.08.2018 14:33, Ilya Maximets wrote:
> Allocation failures of shadow used ring and batched copy array
> are not recoverable and leads to the segmentation faults like
> this on the receiving/transmission path:
> 
>   Program received signal SIGSEGV, Segmentation fault.
>   [Switching to Thread 0x7f913fecf0 (LWP 43625)]
>   in copy_desc_to_mbuf () at /lib/librte_vhost/virtio_net.c:760
>   760       batch_copy[vq->batch_copy_nb_elems].dst =
> 
> This could be easily reproduced in case of low memory or big
> number of vhost-user ports. Fix that by propagating error to
> the upper layer which will end up with disconnection.
> 
> Fixes: f689586bc060 ("vhost: shadow used ring update")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
> ---
>  lib/librte_vhost/vhost_user.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 9aa1ce118..4c7fd57fb 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -1693,7 +1693,9 @@ vhost_user_msg_handler(int vid, int fd)
>  		break;
>  
>  	case VHOST_USER_SET_VRING_NUM:
> -		vhost_user_set_vring_num(dev, &msg);
> +		ret = vhost_user_set_vring_num(dev, &msg);
> +		if (ret)
> +			return -1;
>  		break;
>  	case VHOST_USER_SET_VRING_ADDR:
>  		vhost_user_set_vring_addr(&dev, &msg);
>