diff options
author | Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> | 2019-01-29 09:45:57 +0900 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2019-01-30 14:02:43 -0800 |
commit | 03aa6d34868c07b2b1b8b2db080602d7ec528173 (patch) | |
tree | c4428e7af201285915a27c4295e8a5a57f4167ef /drivers | |
parent | 1667c08a9d31c7cdf09f4890816bfbf20b685495 (diff) |
virtio_net: Don't process redirected XDP frames when XDP is disabled
Commit 8dcc5b0ab0ec ("virtio_net: fix ndo_xdp_xmit crash towards dev not
ready for XDP") tried to avoid access to unexpected sq while XDP is
disabled, but was not complete.
There was a small window which causes out of bounds sq access in
virtnet_xdp_xmit() while disabling XDP.
An example case of
- curr_queue_pairs = 6 (2 for SKB and 4 for XDP)
- online_cpu_num = xdp_queue_paris = 4
when XDP is enabled:
CPU 0 CPU 1
(Disabling XDP) (Processing redirected XDP frames)
virtnet_xdp_xmit()
virtnet_xdp_set()
_virtnet_set_queues()
set curr_queue_pairs (2)
check if rq->xdp_prog is not NULL
virtnet_xdp_sq(vi)
qp = curr_queue_pairs -
xdp_queue_pairs +
smp_processor_id()
= 2 - 4 + 1 = -1
sq = &vi->sq[qp] // out of bounds access
set xdp_queue_pairs (0)
rq->xdp_prog = NULL
Basically we should not change curr_queue_pairs and xdp_queue_pairs
while someone can read the values. Thus, when disabling XDP, assign NULL
to rq->xdp_prog first, and wait for RCU grace period, then change
xxx_queue_pairs.
Note that we need to keep the current order when enabling XDP though.
- v2: Make rcu_assign_pointer/synchronize_net conditional instead of
_virtnet_set_queues.
Fixes: 186b3c998c50 ("virtio-net: support XDP_REDIRECT")
Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/net/virtio_net.c | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 669b65c232a2..cea52e47dc65 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2410,6 +2410,10 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, return -ENOMEM; } + old_prog = rtnl_dereference(vi->rq[0].xdp_prog); + if (!prog && !old_prog) + return 0; + if (prog) { prog = bpf_prog_add(prog, vi->max_queue_pairs - 1); if (IS_ERR(prog)) @@ -2424,21 +2428,30 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, } } + if (!prog) { + for (i = 0; i < vi->max_queue_pairs; i++) { + rcu_assign_pointer(vi->rq[i].xdp_prog, prog); + if (i == 0) + virtnet_restore_guest_offloads(vi); + } + synchronize_net(); + } + err = _virtnet_set_queues(vi, curr_qp + xdp_qp); if (err) goto err; netif_set_real_num_rx_queues(dev, curr_qp + xdp_qp); vi->xdp_queue_pairs = xdp_qp; - for (i = 0; i < vi->max_queue_pairs; i++) { - old_prog = rtnl_dereference(vi->rq[i].xdp_prog); - rcu_assign_pointer(vi->rq[i].xdp_prog, prog); - if (i == 0) { - if (!old_prog) + if (prog) { + for (i = 0; i < vi->max_queue_pairs; i++) { + rcu_assign_pointer(vi->rq[i].xdp_prog, prog); + if (i == 0 && !old_prog) virtnet_clear_guest_offloads(vi); - if (!prog) - virtnet_restore_guest_offloads(vi); } + } + + for (i = 0; i < vi->max_queue_pairs; i++) { if (old_prog) bpf_prog_put(old_prog); if (netif_running(dev)) { @@ -2451,6 +2464,12 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, return 0; err: + if (!prog) { + virtnet_clear_guest_offloads(vi); + for (i = 0; i < vi->max_queue_pairs; i++) + rcu_assign_pointer(vi->rq[i].xdp_prog, old_prog); + } + if (netif_running(dev)) { for (i = 0; i < vi->max_queue_pairs; i++) { virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi); |