在 2021/5/31 下午3:19, Yongji Xie 写道:
On Mon, May 31, 2021 at 2:49 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
在 2021/5/28 下午8:11, Xie Yongji 写道:
This adds validation for used length (might come
from an untrusted device) to avoid data corruption
or loss.
Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
---
drivers/net/virtio_net.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 073fec4c0df1..01f15b65824c 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -732,6 +732,17 @@ static struct sk_buff *receive_small(struct net_device *dev,
rcu_read_lock();
xdp_prog = rcu_dereference(rq->xdp_prog);
+ if (unlikely(len > GOOD_PACKET_LEN)) {
+ pr_debug("%s: rx error: len %u exceeds max size %d\n",
+ dev->name, len, GOOD_PACKET_LEN);
+ dev->stats.rx_length_errors++;
+ if (xdp_prog)
+ goto err_xdp;
+
+ rcu_read_unlock();
+ put_page(page);
+ return NULL;
+ }
if (xdp_prog) {
struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset;
struct xdp_frame *xdpf;
@@ -888,6 +899,16 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
rcu_read_lock();
xdp_prog = rcu_dereference(rq->xdp_prog);
+ if (unlikely(len > truesize)) {
+ pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
+ dev->name, len, (unsigned long)ctx);
+ dev->stats.rx_length_errors++;
+ if (xdp_prog)
+ goto err_xdp;
+
+ rcu_read_unlock();
+ goto err_skb;
+ }
Patch looks correct but I'd rather not bother XDP here. It would be
better if we just do the check before rcu_read_lock() and use err_skb
directly() to avoid RCU/XDP stuffs.
If so, we will miss the statistics of xdp_drops. Is it OK?
It should be ok, we still had drops and it was dropped before dealing
with XDP.
The motivation is to have simple codes.
Thanks
Thanks,
Yongji
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