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Tsirkin" , virtualization , netdev@vger.kernel.org, linux-kernel References: <20210525045838.1137-1-xieyongji@bytedance.com> <75e26cf1-6ee8-108c-ff48-8a23345b3ccc@redhat.com> From: Jason Wang Message-ID: Date: Wed, 26 May 2021 15:52:03 +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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2021/5/25 下午4:45, Yongji Xie 写道: > On Tue, May 25, 2021 at 2:30 PM Jason Wang wrote: >> >> 在 2021/5/25 下午12:58, 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 >>> --- >>> drivers/net/virtio_net.c | 22 ++++++++++++++++++++++ >>> 1 file changed, 22 insertions(+) >>> >>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>> index c4711e23af88..2dcdc1a3c7e8 100644 >>> --- a/drivers/net/virtio_net.c >>> +++ b/drivers/net/virtio_net.c >>> @@ -668,6 +668,13 @@ static struct sk_buff *receive_small(struct net_device *dev, >>> void *orig_data; >>> u32 act; >>> >>> + if (unlikely(len > GOOD_PACKET_LEN)) { >>> + pr_debug("%s: rx error: len %u exceeds max size %lu\n", >>> + dev->name, len, GOOD_PACKET_LEN); >>> + dev->stats.rx_length_errors++; >>> + goto err_xdp; >>> + } >> >> Need to count vi->hdr_len here? >> > We did len -= vi->hdr_len before. Right. > >>> + >>> if (unlikely(hdr->hdr.gso_type)) >>> goto err_xdp; >>> >>> @@ -739,6 +746,14 @@ static struct sk_buff *receive_small(struct net_device *dev, >>> } >>> rcu_read_unlock(); >>> >>> + if (unlikely(len > GOOD_PACKET_LEN)) { >>> + pr_debug("%s: rx error: len %u exceeds max size %lu\n", >>> + dev->name, len, GOOD_PACKET_LEN); >>> + dev->stats.rx_length_errors++; >>> + put_page(page); >>> + return NULL; >>> + } >>> + >>> skb = build_skb(buf, buflen); >>> if (!skb) { >>> put_page(page); >>> @@ -822,6 +837,13 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, >>> void *data; >>> u32 act; >>> >>> + 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_xdp; >>> + } >> >> There's a similar check after the XDP, let's simply move it here? > Do we still need that in non-XDP cases? I meant we check once for both XDP and non-XDP if we do it before if (xdp_prog) > >> And do we need similar check in receive_big()? >> > It seems that the check in page_to_skb() can do similar things. Right. Thanks > > Thanks, > Yongji >