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authorJesper Dangaard Brouer <brouer@redhat.com>2018-02-20 16:32:20 +0300
committerDavid S. Miller <davem@davemloft.net>2018-02-21 23:09:29 +0300
commit8dcc5b0ab0ec9a2efb3362d380272546b8b2ee26 (patch)
tree5986e0b30af64482afd65ea8e6013cf2fff241bb /drivers/net
parent11b7d897ccc1fb5a3d3f9eb1e6b4574671e5dd7d (diff)
downloadlinux-8dcc5b0ab0ec9a2efb3362d380272546b8b2ee26.tar.xz
virtio_net: fix ndo_xdp_xmit crash towards dev not ready for XDP
When a driver implements the ndo_xdp_xmit() function, there is (currently) no generic way to determine whether it is safe to call. It is e.g. unsafe to call the drivers ndo_xdp_xmit, if it have not allocated the needed XDP TX queues yet. This is the case for virtio_net, which first allocates the XDP TX queues once an XDP/bpf prog is attached (in virtnet_xdp_set()). Thus, a crash will occur for virtio_net when redirecting to another virtio_net device's ndo_xdp_xmit, which have not attached a XDP prog. The sample xdp_redirect_map tries to attach a dummy XDP prog to take this into account, but it can also easily fail if the virtio_net (or actually underlying vhost driver) have not allocated enough extra queues for the device. Allocating more queue this is currently a manual config. Hint for libvirt XML add: <driver name='vhost' queues='16'> <host mrg_rxbuf='off'/> <guest tso4='off' tso6='off' ecn='off' ufo='off'/> </driver> The solution in this patch is to check that the device have loaded an XDP/bpf prog before proceeding. This is similar to the check performed in driver ixgbe. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/virtio_net.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 1e0e0fce3ab2..9bb9e562b893 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -452,8 +452,18 @@ static bool __virtnet_xdp_xmit(struct virtnet_info *vi,
static int virtnet_xdp_xmit(struct net_device *dev, struct xdp_buff *xdp)
{
struct virtnet_info *vi = netdev_priv(dev);
- bool sent = __virtnet_xdp_xmit(vi, xdp);
+ struct receive_queue *rq = vi->rq;
+ struct bpf_prog *xdp_prog;
+ bool sent;
+
+ /* Only allow ndo_xdp_xmit if XDP is loaded on dev, as this
+ * indicate XDP resources have been successfully allocated.
+ */
+ xdp_prog = rcu_dereference(rq->xdp_prog);
+ if (!xdp_prog)
+ return -ENXIO;
+ sent = __virtnet_xdp_xmit(vi, xdp);
if (!sent)
return -ENOSPC;
return 0;