[PATCH 5.13 056/266] virtio-net: Add validation for used length

Greg Kroah-Hartman
2021-07-15T19:28:49Z

From: Xie Yongji <xieyongji@bytedance.com>

[ Upstream commit ad993a95c508417acdeb15244109e009e50d8758 ]

This adds validation for used length (might come
from an untrusted device) to avoid data corruption
or loss.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210531135852.113-1-xieyongji@bytedance.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/virtio_net.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 78a01c71a17c..252f6718d730 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -721,6 +721,12 @@ static struct sk_buff *receive_small(struct net_device *dev,
len -= vi->hdr_len;
stats->bytes += len;

+ 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++;
+ goto err_len;
+ }
rcu_read_lock();
xdp_prog = rcu_dereference(rq->xdp_prog);
if (xdp_prog) {
@@ -824,6 +830,7 @@ err:
err_xdp:
rcu_read_unlock();
stats->xdp_drops++;
+err_len:
stats->drops++;
put_page(page);
xdp_xmit:
@@ -877,6 +884,12 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
head_skb = NULL;
stats->bytes += len - vi->hdr_len;

+ 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++;
+ goto err_skb;
+ }
rcu_read_lock();
xdp_prog = rcu_dereference(rq->xdp_prog);
if (xdp_prog) {
@@ -1004,13 +1017,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
}
rcu_read_unlock();

- 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++;
- goto err_skb;
- }
-
head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog,
metasize, headroom);
curr_skb = head_skb;
--
2.30.2