On 15.07.2016 09:17, Yuanhan Liu wrote:
> On Thu, Jul 14, 2016 at 11:18:39AM +0300, Ilya Maximets wrote:
>> In current implementation vhost will crash with segmentation fault
>> if malicious or buggy virtio application breaks addresses of descriptors.
>>
>> Before commit 0823c1cb0a73 this crash was reproducible even with
>> normal DPDK application that tries to change number of virtqueues
>> dynamically inside VM.
>>
>> Fix that by checking addresses of descriptors before using.
>>
>> Also fixed return value on error for 'copy_mbuf_to_desc_mergeable()'
>> from '-1' to '0' because it returns unsigned value and it means
>> number of used descriptors.
>
> Yeah, that's a good fix. Thanks.
>
> Maybe you'd better make it a standalone patch.
Ok. Maybe I should split this patch in two:
1. Fix return value + using of this value (vq->last_used_idx += nr_used;)
2. Check addresses of descriptors.
What do you think?
>> Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
>> ---
>> Version 2:
>> * Rebased on top of current master.
>> * host's address now checked in meargeable case,
>> because needed refactoring already done.
>> * Commit-message changed because old issue with
>> virtio reload accidentially fixed by commit
>> 0823c1cb0a73.
>>
>> lib/librte_vhost/vhost_rxtx.c | 28 +++++++++++++++++++++-------
>> 1 file changed, 21 insertions(+), 7 deletions(-)
>>
>> diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
>> index 15ca956..31e8b58 100644
>> --- a/lib/librte_vhost/vhost_rxtx.c
>> +++ b/lib/librte_vhost/vhost_rxtx.c
>> @@ -147,10 +147,10 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct
>> vhost_virtqueue *vq,
>> struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
>>
>> desc = &vq->desc[desc_idx];
>> - if (unlikely(desc->len < dev->vhost_hlen))
>> + desc_addr = gpa_to_vva(dev, desc->addr);
>> + if (unlikely(desc->len < dev->vhost_hlen || !desc_addr))
>> return -1;
>
> So, you discards the workaround from Rich?
I can apply it, if you wish. Should I?
>>
>> - desc_addr = gpa_to_vva(dev, desc->addr);
>> rte_prefetch0((void *)(uintptr_t)desc_addr);
>>
>> virtio_enqueue_offload(m, &virtio_hdr.hdr);
>> @@ -182,7 +182,10 @@ copy_mbuf_to_desc(struct virtio_net *dev, struct
>> vhost_virtqueue *vq,
>> return -1;
>>
>> desc = &vq->desc[desc->next];
>> - desc_addr = gpa_to_vva(dev, desc->addr);
>> + desc_addr = gpa_to_vva(dev, desc->addr);
>> + if (unlikely(!desc_addr))
>> + return -1;
>> +
>> desc_offset = 0;
>> desc_avail = desc->len;
>> }
>> @@ -387,10 +390,10 @@ copy_mbuf_to_desc_mergeable(struct virtio_net *dev,
>> struct vhost_virtqueue *vq,
>> LOG_DEBUG(VHOST_DATA, "(%d) current index %d | end index %d\n",
>> dev->vid, cur_idx, end_idx);
>>
>> - if (buf_vec[vec_idx].buf_len < dev->vhost_hlen)
>> - return -1;
>> -
>> desc_addr = gpa_to_vva(dev, buf_vec[vec_idx].buf_addr);
>> + if (buf_vec[vec_idx].buf_len < dev->vhost_hlen || !desc_addr)
>> + return 0;
>> +
>> rte_prefetch0((void *)(uintptr_t)desc_addr);
>>
>> virtio_hdr.num_buffers = end_idx - start_idx;
>> @@ -425,6 +428,8 @@ copy_mbuf_to_desc_mergeable(struct virtio_net *dev,
>> struct vhost_virtqueue *vq,
>>
>> vec_idx++;
>> desc_addr = gpa_to_vva(dev, buf_vec[vec_idx].buf_addr);
>> + if (unlikely(!desc_addr))
>> + return 0;
>>
>> /* Prefetch buffer address. */
>> rte_prefetch0((void *)(uintptr_t)desc_addr);
>> @@ -507,7 +512,7 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t
>> queue_id,
>> *(volatile uint16_t *)&vq->used->idx += nr_used;
>> vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
>> sizeof(vq->used->idx));
>> - vq->last_used_idx = end;
>> + vq->last_used_idx += nr_used;
>
> Ditto, this may deserve another patch, too.
>
> --yliu
>
>
