Re: [PATCH] net/vhost: fix access to freed memory

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Hi Yuan,

On 3/11/22 17:35, Yuan Wang wrote:
> This patch fixes heap-use-after-free reported by ASan.
> 
> It is possible for the rte_vhost_dequeue_burst() to access the vq
> is freed when numa_realloc() gets called in the device running state.
> The control plane will set the vq->access_lock to protected the vq
> from the data plane. Unfortunately the lock will fail at the moment
> the vq is freed, allowing the rte_vhost_dequeue_burst() to access
> the fields of the vq, which will trigger a heap-use-after-free error.
> 
> In the case of multiple queues, the vhost pmd can access other queues
> that are not ready when the first queue is ready, which makes no sense
> and also allows numa_realloc() and rte_vhost_dequeue_burst() access to
> vq to happen at the same time. By controlling vq->allow_queuing we can make
> the pmd access only the queues that are ready.
> 
> Fixes: 1ce3c7fe149 ("net/vhost: emulate device start/stop behavior")
> 
> Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
> ---
>   drivers/net/vhost/rte_eth_vhost.c | 15 +++++++++++++--
>   1 file changed, 13 insertions(+), 2 deletions(-)
> 
It is indeed better for the Vhost PMD to not access virtqueues that
aren't ready.

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime