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Mon, 31 May 2021 18:51:57 -0700 (PDT) Received: from wangxiaodeMacBook-Air.local ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id k12sm7581515pga.13.2021.05.31.18.51.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 May 2021 18:51:57 -0700 (PDT) Subject: Re: [PATCH v4] virtio-net: Add validation for used length To: Xie Yongji , mst@redhat.com, kuba@kernel.org Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210531135852.113-1-xieyongji@bytedance.com> From: Jason Wang Message-ID: <32febeff-cc36-2333-5d2c-1f3ae3d91f94@redhat.com> Date: Tue, 1 Jun 2021 09:51:53 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: <20210531135852.113-1-xieyongji@bytedance.com> Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2021/5/31 ÏÂÎç9:58, Xie Yongji дµÀ: > This adds validation for used length (might come > from an untrusted device) to avoid data corruption > or loss. > > Signed-off-by: Xie Yongji Acked-by: Jason Wang > --- > 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 073fec4c0df1..ed969b65126e 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -730,6 +730,12 @@ 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) { > @@ -833,6 +839,7 @@ static struct sk_buff *receive_small(struct net_device *dev, > err_xdp: > rcu_read_unlock(); > stats->xdp_drops++; > +err_len: > stats->drops++; > put_page(page); > xdp_xmit: > @@ -886,6 +893,12 @@ 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) { > @@ -1012,13 +1025,6 @@ 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;