Re: [Qemu-devel] net: vmxnet3: memory leakage issue

[Jason Wang <jasowang@redhat.com>]

On 12/03/2015 03:17 PM, Dmitry Fleytman wrote:
> Hello Prasad,
>
> The patch is good.
> Jason, would you apply is from attachment or should it be resent by
> "git send-email”?

Better with "git send-email". And I've a question for this patch which
needs to be answered before merging this.

What if guest deactivate the device before re-activate the device?

Thanks

>
> Acked-by: Dmitry Fleytman <dmitry@daynix.com <mailto:dmitry@daynix.com>>
>
> ~Dmitry
>
>> On 2 Dec 2015, at 14:17 PM, P J P <ppandit@redhat.com
>> <mailto:ppandit@redhat.com>> wrote:
>>
>>  Hello Dmitry, all
>>
>> A memory leakage issue was reported by Mr Qinghao Tang, CC'd here.
>>
>> In that, the Qemu VMXNET3 paravirtual device emulator does not check
>> if the device is already active, before activating it. This leads to
>> host memory leakage via calls to vmxnet_tx_pkt_init(), which calls
>> g_malloc0().
>>
>> ===
>> static void vmxnet3_activate_device(VMXNET3State *s)
>> {
>>   ...
>>   /* Preallocate TX packet wrapper */
>>   VMW_CFPRN("Max TX fragments is %u", s->max_tx_frags);
>>   vmxnet_tx_pkt_init(&s->tx_pkt, s->max_tx_frags, s->peer_has_vhdr);
>>   ...
>> }
>> ===
>>
>> A malicious guest driver could use this flaw to leak excessive memory
>> on the host, eventually killing the Qemu process.
>>
>> Please see attached herein is a proposed (tested)patch which fixes
>> this issue. Please let me know if it's okay or requires any changes.
>>
>> Thank you.
>> --
>> Prasad J Pandit / Red Hat Product Security Team
>> 47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B
>> 041F<0001-net-vmxnet3-avoid-multiple-activations-of-device.patch>
>