>From 9eea4f61a4dca97f56c23e12267219bf791a20d1 Mon Sep 17 00:00:00 2001
From: Jingguo Tan <[email protected]>
Date: Fri, 22 May 2026 19:53:45 +0800
Subject: [PATCH net] 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 calls 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 <[email protected]>
Signed-off-by: Rongzhen Cui <[email protected]>
Signed-off-by: Jingguo Tan <[email protected]>
---
net/vmw_vsock/virtio_transport_common.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/net/vmw_vsock/virtio_transport_common.c
b/net/vmw_vsock/virtio_transport_common.c
index df3b418e0392..73f58925ff72 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 +246,11 @@ 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 +370,7 @@ 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 +378,6 @@ 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 +1188,7 @@ 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),
--
2.53.0
