From 1e584c304cfb94a759417130b1fc6d30b30c4cce Mon Sep 17 00:00:00 2001 From: Jingguo Tan Date: Wed, 27 May 2026 10:33:01 +0800 Subject: [PATCH] vsock/virtio: bind uarg before filling zerocopy skb virtio_transport_send_pkt_info() allocates or reuses the zerocopy uarg before entering the send loop, but virtio_transport_alloc_skb() still fills the skb before it inherits that uarg. When fixed-buffer vectored zerocopy hits MAX_SKB_FRAGS, io_sg_from_iter() may partially attach managed frags and return -EMSGSIZE. The rollback path call kfree_skb() to free an skb that carries SKBFL_MANAGED_FRAG_REFS but no uarg, so skb_release_data() falls through to ordinary frag unref. Pass the uarg into virtio_transport_alloc_skb() and bind it immediately before virtio_transport_fill_skb(). This keeps control or no-payload skbs untouched while ensuring success and rollback share one lifetime rule. Fixes: 581512a6dc93 ("vsock/virtio: MSG_ZEROCOPY flag support") Signed-off-by: Lin Ma Signed-off-by: Rongzhen Cui Signed-off-by: Jingguo Tan Acked-by: Arseniy Krasnov Acked-by: Michael S. Tsirkin Reviewed-by: Stefano Garzarella Link: https://patch.msgid.link/20260527023301.1075581-1-malin89@huawei.com Signed-off-by: Jakub Kicinski --- net/vmw_vsock/virtio_transport_common.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index b143290a311d..b10666937c49 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -205,6 +205,7 @@ static u16 virtio_transport_get_type(struct sock *sk) static struct sk_buff *virtio_transport_alloc_skb(struct virtio_vsock_pkt_info *info, size_t payload_len, bool zcopy, + struct ubuf_info *uarg, u32 src_cid, u32 src_port, u32 dst_cid, @@ -245,6 +246,12 @@ static struct sk_buff *virtio_transport_alloc_skb(struct virtio_vsock_pkt_info * if (info->msg && payload_len > 0) { int err; + /* Bind the zerocopy lifetime before filling frags so error + * rollback frees managed fixed-buffer pages through + * the uarg-aware path. + */ + skb_zcopy_set(skb, uarg, NULL); + err = virtio_transport_fill_skb(skb, info, payload_len, zcopy); if (err) goto out; @@ -364,6 +371,7 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, skb_len = min(max_skb_len, rest_len); skb = virtio_transport_alloc_skb(info, skb_len, can_zcopy, + uarg, src_cid, src_port, dst_cid, dst_port); if (!skb) { @@ -371,8 +379,6 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk, break; } - skb_zcopy_set(skb, uarg, NULL); - virtio_transport_inc_tx_pkt(vvs, skb); ret = t_ops->send_pkt(skb, info->net); @@ -1183,7 +1189,7 @@ static int virtio_transport_reset_no_sock(const struct virtio_transport *t, if (!t) return -ENOTCONN; - reply = virtio_transport_alloc_skb(&info, 0, false, + reply = virtio_transport_alloc_skb(&info, 0, false, NULL, le64_to_cpu(hdr->dst_cid), le32_to_cpu(hdr->dst_port), le64_to_cpu(hdr->src_cid),