[Qemu-devel] [PATCH] virtio-net: only delete bh that existed

[Qemu-devel] [PATCH] virtio-net: only delete bh that existed

[Jason Wang]

We delete without check whether it existed during exit. This will lead NULL
pointer deference since it was created conditionally depends on guest driver
status and features. So add a check of existence before trying to delete it.

Cc: qemu-stable@nongnu.org
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/net/virtio-net.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 22dbd05..ae51d96 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1601,7 +1601,7 @@ static int virtio_net_device_exit(DeviceState *qdev)
         if (q->tx_timer) {
             timer_del(q->tx_timer);
             timer_free(q->tx_timer);
-        } else {
+        } else if (q->tx_bh) {
             qemu_bh_delete(q->tx_bh);
         }
     }
-- 
1.8.3.2

Re: [Qemu-devel] [PATCH 1.7] virtio-net: only delete bh that existed

[Paolo Bonzini]

Il 06/11/2013 09:58, Jason Wang ha scritto:
> We delete without check whether it existed during exit. This will lead NULL
> pointer deference since it was created conditionally depends on guest driver
> status and features. So add a check of existence before trying to delete it.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  hw/net/virtio-net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 22dbd05..ae51d96 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1601,7 +1601,7 @@ static int virtio_net_device_exit(DeviceState *qdev)
>          if (q->tx_timer) {
>              timer_del(q->tx_timer);
>              timer_free(q->tx_timer);
> -        } else {
> +        } else if (q->tx_bh) {
>              qemu_bh_delete(q->tx_bh);
>          }
>      }
> 

Please remember to add 1.7 in the subject at this time.

Paolo

Re: [Qemu-devel] [PATCH] virtio-net: only delete bh that existed

[Michael S. Tsirkin]

On Wed, Nov 06, 2013 at 04:58:08PM +0800, Jason Wang wrote:
> We delete without check whether it existed during exit. This will lead NULL
> pointer deference since it was created conditionally depends on guest driver
> status and features. So add a check of existence before trying to delete it.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Looks like the bug was introduced by:
	commit 17ec5a8686143da66208273d355f2eeb09807614
	Author: KONRAD Frederic <fred.konrad@greensocs.com>
	Date:   Thu Apr 11 16:29:57 2013 +0200
	    virtio-net: add the virtio-net device.

Before that we had a single bh and created/destroyed
that unconditionally.
Is this a correct analysis?



> ---
>  hw/net/virtio-net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 22dbd05..ae51d96 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1601,7 +1601,7 @@ static int virtio_net_device_exit(DeviceState *qdev)
>          if (q->tx_timer) {
>              timer_del(q->tx_timer);
>              timer_free(q->tx_timer);
> -        } else {
> +        } else if (q->tx_bh) {
>              qemu_bh_delete(q->tx_bh);
>          }
>      }
> -- 
> 1.8.3.2

Re: [Qemu-devel] [PATCH] virtio-net: only delete bh that existed

[Jason Wang]

On 11/06/2013 07:17 PM, Michael S. Tsirkin wrote:
> On Wed, Nov 06, 2013 at 04:58:08PM +0800, Jason Wang wrote:
>> We delete without check whether it existed during exit. This will lead NULL
>> pointer deference since it was created conditionally depends on guest driver
>> status and features. So add a check of existence before trying to delete it.
>>
>> Cc: qemu-stable@nongnu.org
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
>
> Looks like the bug was introduced by:
> 	commit 17ec5a8686143da66208273d355f2eeb09807614
> 	Author: KONRAD Frederic <fred.konrad@greensocs.com>
> 	Date:   Thu Apr 11 16:29:57 2013 +0200
> 	    virtio-net: add the virtio-net device.
>
> Before that we had a single bh and created/destroyed
> that unconditionally.
> Is this a correct analysis?
>

Nope, it was introduced in the multiqueue virito-net, since the bh were
created conditionally from that commit.

commit fed699f9ca6ae8a0fb62803334cf46fa64d1eb91
Author: Jason Wang <jasowang@redhat.com>
Date:   Wed Jan 30 19:12:39 2013 +0800

    virtio-net: multiqueue support
>
>> ---
>>  hw/net/virtio-net.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>> index 22dbd05..ae51d96 100644
>> --- a/hw/net/virtio-net.c
>> +++ b/hw/net/virtio-net.c
>> @@ -1601,7 +1601,7 @@ static int virtio_net_device_exit(DeviceState *qdev)
>>          if (q->tx_timer) {
>>              timer_del(q->tx_timer);
>>              timer_free(q->tx_timer);
>> -        } else {
>> +        } else if (q->tx_bh) {
>>              qemu_bh_delete(q->tx_bh);
>>          }
>>      }
>> -- 
>> 1.8.3.2