From: Xie Yongji <xieyongji@bytedance.com>
Date: Mon, 31 May 2021 13:58:52 +0000 (+0800)
Subject: virtio-net: Add validation for used length
X-Git-Tag: v5.4.293~56
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c1b40d1959517ff2ea473d40eeab4691d6d62462;p=thirdparty%2Fkernel%2Fstable.git

virtio-net: Add validation for used length

commit ad993a95c508417acdeb15244109e009e50d8758 upstream.

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>
[ Larry: backport to 5.4.y. Minor conflict resolved due to missing commit 9ce6146ec7b50
  virtio_net: Add XDP frame size in two code paths ]
Signed-off-by: Larry Bassel <larry.bassel@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 182b672700442..215c546bf50a9 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -717,6 +717,12 @@ 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) {
@@ -819,6 +825,7 @@ err:
 err_xdp:
 	rcu_read_unlock();
 	stats->xdp_drops++;
+err_len:
 	stats->drops++;
 	put_page(page);
 xdp_xmit:
@@ -871,6 +878,13 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	head_skb = NULL;
 	stats->bytes += len - vi->hdr_len;
 
+	truesize = mergeable_ctx_to_truesize(ctx);
+	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) {
@@ -990,14 +1004,6 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	}
 	rcu_read_unlock();
 
-	truesize = mergeable_ctx_to_truesize(ctx);
-	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);
 	curr_skb = head_skb;