[PATCH net V2] virtio-net: drop NETIF_F_FRAGLIST

[PATCH net V2] virtio-net: drop NETIF_F_FRAGLIST

[Jason Wang]

virtio declares support for NETIF_F_FRAGLIST, but assumes
that there are at most MAX_SKB_FRAGS + 2 fragments which isn't
always true with a fraglist.

A longer fraglist in the skb will make the call to skb_to_sgvec overflow
the sg array, leading to memory corruption.

Drop NETIF_F_FRAGLIST so we only get what we can handle.

Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
- Change from V1: coding style fixes.
- The patch is needed for stable.
---
 drivers/net/virtio_net.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7fbca37..237f8e5 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1756,9 +1756,9 @@ static int virtnet_probe(struct virtio_device *vdev)
 	/* Do we support "hardware" checksums? */
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
 		/* This opens up the world of extra features. */
-		dev->hw_features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
+		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
 		if (csum)
-			dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
+			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
 
 		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
 			dev->hw_features |= NETIF_F_TSO | NETIF_F_UFO
-- 
2.1.4

Re: [PATCH net V2] virtio-net: drop NETIF_F_FRAGLIST

[Michael S. Tsirkin]

On Wed, Aug 05, 2015 at 10:34:04AM +0800, Jason Wang wrote:
> virtio declares support for NETIF_F_FRAGLIST, but assumes
> that there are at most MAX_SKB_FRAGS + 2 fragments which isn't
> always true with a fraglist.
> 
> A longer fraglist in the skb will make the call to skb_to_sgvec overflow
> the sg array, leading to memory corruption.
> 
> Drop NETIF_F_FRAGLIST so we only get what we can handle.
> 
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

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

> ---
> - Change from V1: coding style fixes.
> - The patch is needed for stable.
> ---
>  drivers/net/virtio_net.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7fbca37..237f8e5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1756,9 +1756,9 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	/* Do we support "hardware" checksums? */
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
>  		/* This opens up the world of extra features. */
> -		dev->hw_features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
> +		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
>  		if (csum)
> -			dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
> +			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
>  
>  		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
>  			dev->hw_features |= NETIF_F_TSO | NETIF_F_UFO
> -- 
> 2.1.4

Re: [PATCH net V2] virtio-net: drop NETIF_F_FRAGLIST

[Michael S. Tsirkin]

On Wed, Aug 05, 2015 at 10:34:04AM +0800, Jason Wang wrote:
> virtio declares support for NETIF_F_FRAGLIST, but assumes
> that there are at most MAX_SKB_FRAGS + 2 fragments which isn't
> always true with a fraglist.
> 
> A longer fraglist in the skb will make the call to skb_to_sgvec overflow
> the sg array, leading to memory corruption.
> 
> Drop NETIF_F_FRAGLIST so we only get what we can handle.
> 
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

I noticed only now that this didn't Cc Dave, so of course it's
not applied. I'm preparing a pull request anyway, so
I'll merge this through my tree, and add Cc stable.
Dave - ok with you?

> ---
> - Change from V1: coding style fixes.
> - The patch is needed for stable.
> ---
>  drivers/net/virtio_net.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7fbca37..237f8e5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1756,9 +1756,9 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	/* Do we support "hardware" checksums? */
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
>  		/* This opens up the world of extra features. */
> -		dev->hw_features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
> +		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
>  		if (csum)
> -			dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
> +			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
>  
>  		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
>  			dev->hw_features |= NETIF_F_TSO | NETIF_F_UFO
> -- 
> 2.1.4

Re: [PATCH net V2] virtio-net: drop NETIF_F_FRAGLIST

[David Miller]

From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Thu, 6 Aug 2015 16:13:11 +0300

> On Wed, Aug 05, 2015 at 10:34:04AM +0800, Jason Wang wrote:
>> virtio declares support for NETIF_F_FRAGLIST, but assumes
>> that there are at most MAX_SKB_FRAGS + 2 fragments which isn't
>> always true with a fraglist.
>> 
>> A longer fraglist in the skb will make the call to skb_to_sgvec overflow
>> the sg array, leading to memory corruption.
>> 
>> Drop NETIF_F_FRAGLIST so we only get what we can handle.
>> 
>> Cc: Michael S. Tsirkin <mst@redhat.com>
>> Signed-off-by: Jason Wang <jasowang@redhat.com>
> 
> I noticed only now that this didn't Cc Dave, so of course it's
> not applied.

CC:'ing me isn't the requirement. CC:'ing netdev is, which he
did.  If you check patchwork, it's there in the queue.

I'm just behind and heavily backlogged because I've been working
on other things.

Re: [PATCH net V2] virtio-net: drop NETIF_F_FRAGLIST

[David Miller]

From: Jason Wang <jasowang@redhat.com>
Date: Wed,  5 Aug 2015 10:34:04 +0800

> virtio declares support for NETIF_F_FRAGLIST, but assumes
> that there are at most MAX_SKB_FRAGS + 2 fragments which isn't
> always true with a fraglist.
> 
> A longer fraglist in the skb will make the call to skb_to_sgvec overflow
> the sg array, leading to memory corruption.
> 
> Drop NETIF_F_FRAGLIST so we only get what we can handle.
> 
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Applied, thanks Jason.