Re: [PATCH] net: vmxnet3: validate configuration values during activate (CVE-2021-20203)

[P J P]

On Monday, 18 October, 2021, 12:20:55 pm IST, Thomas Huth <thuth@redhat.com> 
wrote:
On 30/01/2021 14.16, P J P wrote:
>> diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
>> index eff299f629..4a910ca971 100644
>> --- a/hw/net/vmxnet3.c
>> +++ b/hw/net/vmxnet3.c
>> @@ -1420,6 +1420,7 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>>      vmxnet3_setup_rx_filtering(s);
>>      /* Cache fields from shared memory */
>>      s->mtu = VMXNET3_READ_DRV_SHARED32(d, s->drv_shmem, devRead.misc.mtu);
>> +    assert(VMXNET3_MIN_MTU <= s->mtu && s->mtu < VMXNET3_MAX_MTU);
>>      VMW_CFPRN("MTU is %u", s->mtu);
>>  
>>      s->max_rx_frags =
>> @@ -1473,6 +1474,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>>          /* Read rings memory locations for TX queues */
>>          pa = VMXNET3_READ_TX_QUEUE_DESCR64(d, qdescr_pa, conf.txRingBasePA);
>>          size = VMXNET3_READ_TX_QUEUE_DESCR32(d, qdescr_pa, conf.txRingSize);
>> +        if (size > VMXNET3_TX_RING_MAX_SIZE) {
>> +            size = VMXNET3_TX_RING_MAX_SIZE;
>> +        }
>>  
>>          vmxnet3_ring_init(d, &s->txq_descr[i].tx_ring, pa, size,
>>                            sizeof(struct Vmxnet3_TxDesc), false);
>> @@ -1483,6 +1487,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>>          /* TXC ring */
>>          pa = VMXNET3_READ_TX_QUEUE_DESCR64(d, qdescr_pa, 
>>conf.compRingBasePA);
>>          size = VMXNET3_READ_TX_QUEUE_DESCR32(d, qdescr_pa, 
>>conf.compRingSize);
>> +        if (size > VMXNET3_TC_RING_MAX_SIZE) {
>> +            size = VMXNET3_TC_RING_MAX_SIZE;
>> +        }
>>          vmxnet3_ring_init(d, &s->txq_descr[i].comp_ring, pa, size,
>>                            sizeof(struct Vmxnet3_TxCompDesc), true);
>>          VMXNET3_RING_DUMP(VMW_CFPRN, "TXC", i, &s->txq_descr[i].comp_ring);
>> @@ -1524,6 +1531,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>>              /* RX rings */
>>              pa = VMXNET3_READ_RX_QUEUE_DESCR64(d, qd_pa, 
>>conf.rxRingBasePA[j]);
>>              size = VMXNET3_READ_RX_QUEUE_DESCR32(d, qd_pa, 
>>conf.rxRingSize[j]);
>> +            if (size > VMXNET3_RX_RING_MAX_SIZE) {
>> +                size = VMXNET3_RX_RING_MAX_SIZE;
>> +            }
>>              vmxnet3_ring_init(d, &s->rxq_descr[i].rx_ring[j], pa, size,
>>                                sizeof(struct Vmxnet3_RxDesc), false);
>>              VMW_CFPRN("RX queue %d:%d: Base: %" PRIx64 ", Size: %d",
>> @@ -1533,6 +1543,9 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>>          /* RXC ring */
>>          pa = VMXNET3_READ_RX_QUEUE_DESCR64(d, qd_pa, conf.compRingBasePA);
>>          size = VMXNET3_READ_RX_QUEUE_DESCR32(d, qd_pa, conf.compRingSize);
>> +        if (size > VMXNET3_RC_RING_MAX_SIZE) {
>> +            size = VMXNET3_RC_RING_MAX_SIZE;
>> +        }
>>          vmxnet3_ring_init(d, &s->rxq_descr[i].comp_ring, pa, size,
>>                            sizeof(struct Vmxnet3_RxCompDesc), true);
>>          VMW_CFPRN("RXC queue %d: Base: %" PRIx64 ", Size: %d", i, pa, size);
>> 
>>
>Ping!
>
>According to 
>https://gitlab.com/qemu-project/qemu/-/issues/308#note_705736713 this is 
>still an issue...
>
>Patch looks fine to me ... maybe just add some 
>qemu_log_mask(LOG_GUEST_ERROR, ...) statements before correcting the values?


* Oops! Not sure how I missed it, thought it was pulled upstream.
  Will send a revised patch.


Thank you.
---
  - P J P