From c3838262b824c71c145cd3668722e99a69bc9cd9 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Fri, 31 Oct 2025 14:05:51 +0800 Subject: virtio_net: fix alignment for virtio_net_hdr_v1_hash Changing alignment of header would mean it's no longer safe to cast a 2 byte aligned pointer between formats. Use two 16 bit fields to make it 2 byte aligned as previously. This fixes the performance regression since commit ("virtio_net: enable gso over UDP tunnel support.") as it uses virtio_net_hdr_v1_hash_tunnel which embeds virtio_net_hdr_v1_hash. Pktgen in guest + XDP_DROP on TAP + vhost_net shows the TX PPS is recovered from 2.4Mpps to 4.45Mpps. Fixes: 56a06bd40fab ("virtio_net: enable gso over UDP tunnel support.") Cc: stable@vger.kernel.org Signed-off-by: Michael S. Tsirkin Signed-off-by: Jason Wang Tested-by: Lei Yang Link: https://patch.msgid.link/20251031060551.126-1-jasowang@redhat.com Signed-off-by: Jakub Kicinski --- drivers/net/virtio_net.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'drivers/net/virtio_net.c') diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 8e8a179aaa49..e6e650bc3bc3 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2539,6 +2539,13 @@ err_buf: return NULL; } +static inline u32 +virtio_net_hash_value(const struct virtio_net_hdr_v1_hash *hdr_hash) +{ + return __le16_to_cpu(hdr_hash->hash_value_lo) | + (__le16_to_cpu(hdr_hash->hash_value_hi) << 16); +} + static void virtio_skb_set_hash(const struct virtio_net_hdr_v1_hash *hdr_hash, struct sk_buff *skb) { @@ -2565,7 +2572,7 @@ static void virtio_skb_set_hash(const struct virtio_net_hdr_v1_hash *hdr_hash, default: rss_hash_type = PKT_HASH_TYPE_NONE; } - skb_set_hash(skb, __le32_to_cpu(hdr_hash->hash_value), rss_hash_type); + skb_set_hash(skb, virtio_net_hash_value(hdr_hash), rss_hash_type); } static void virtnet_receive_done(struct virtnet_info *vi, struct receive_queue *rq, @@ -3311,6 +3318,10 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb, bool orphan) pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest); + /* Make sure it's safe to cast between formats */ + BUILD_BUG_ON(__alignof__(*hdr) != __alignof__(hdr->hash_hdr)); + BUILD_BUG_ON(__alignof__(*hdr) != __alignof__(hdr->hash_hdr.hdr)); + can_push = vi->any_header_sg && !((unsigned long)skb->data & (__alignof__(*hdr) - 1)) && !skb_header_cloned(skb) && skb_headroom(skb) >= hdr_len; @@ -6750,7 +6761,7 @@ static int virtnet_xdp_rx_hash(const struct xdp_md *_ctx, u32 *hash, hash_report = VIRTIO_NET_HASH_REPORT_NONE; *rss_type = virtnet_xdp_rss_type[hash_report]; - *hash = __le32_to_cpu(hdr_hash->hash_value); + *hash = virtio_net_hash_value(hdr_hash); return 0; } -- cgit v1.2.3 From 0c716703965ffc5ef4311b65cb5d84a703784717 Mon Sep 17 00:00:00 2001 From: Bui Quang Minh Date: Thu, 30 Oct 2025 21:44:38 +0700 Subject: virtio-net: fix received length check in big packets Since commit 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big packets"), when guest gso is off, the allocated size for big packets is not MAX_SKB_FRAGS * PAGE_SIZE anymore but depends on negotiated MTU. The number of allocated frags for big packets is stored in vi->big_packets_num_skbfrags. Because the host announced buffer length can be malicious (e.g. the host vhost_net driver's get_rx_bufs is modified to announce incorrect length), we need a check in virtio_net receive path. Currently, the check is not adapted to the new change which can lead to NULL page pointer dereference in the below while loop when receiving length that is larger than the allocated one. This commit fixes the received length check corresponding to the new change. Fixes: 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big packets") Cc: stable@vger.kernel.org Signed-off-by: Bui Quang Minh Reviewed-by: Xuan Zhuo Tested-by: Lei Yang Link: https://patch.msgid.link/20251030144438.7582-1-minhquangbui99@gmail.com Signed-off-by: Jakub Kicinski --- drivers/net/virtio_net.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) (limited to 'drivers/net/virtio_net.c') diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index e6e650bc3bc3..8855a994e12b 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -910,17 +910,6 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi, goto ok; } - /* - * Verify that we can indeed put this data into a skb. - * This is here to handle cases when the device erroneously - * tries to receive more than is possible. This is usually - * the case of a broken device. - */ - if (unlikely(len > MAX_SKB_FRAGS * PAGE_SIZE)) { - net_dbg_ratelimited("%s: too much data\n", skb->dev->name); - dev_kfree_skb(skb); - return NULL; - } BUG_ON(offset >= PAGE_SIZE); while (len) { unsigned int frag_size = min((unsigned)PAGE_SIZE - offset, len); @@ -2112,9 +2101,19 @@ static struct sk_buff *receive_big(struct net_device *dev, struct virtnet_rq_stats *stats) { struct page *page = buf; - struct sk_buff *skb = - page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, 0); + struct sk_buff *skb; + + /* Make sure that len does not exceed the size allocated in + * add_recvbuf_big. + */ + if (unlikely(len > (vi->big_packets_num_skbfrags + 1) * PAGE_SIZE)) { + pr_debug("%s: rx error: len %u exceeds allocated size %lu\n", + dev->name, len, + (vi->big_packets_num_skbfrags + 1) * PAGE_SIZE); + goto err; + } + skb = page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, 0); u64_stats_add(&stats->bytes, len - vi->hdr_len); if (unlikely(!skb)) goto err; -- cgit v1.2.3