Patch "vsock/virtio: fix potential unbounded skb queue" has been added to the 6.6-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    vsock/virtio: fix potential unbounded skb queue

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     vsock-virtio-fix-potential-unbounded-skb-queue.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From 059b7dbd20a6f0c539a45ddff1573cb8946685b5 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Thu, 30 Apr 2026 12:26:52 +0000
Subject: vsock/virtio: fix potential unbounded skb queue
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Eric Dumazet <edumazet@google.com>

commit 059b7dbd20a6f0c539a45ddff1573cb8946685b5 upstream.

virtio_transport_inc_rx_pkt() checks vvs->rx_bytes + len > vvs->buf_alloc.

virtio_transport_recv_enqueue() skips coalescing for packets
with VIRTIO_VSOCK_SEQ_EOM.

If fed with packets with len == 0 and VIRTIO_VSOCK_SEQ_EOM,
a very large number of packets can be queued
because vvs->rx_bytes stays at 0.

Fix this by estimating the skb metadata size:

	(Number of skbs in the queue) * SKB_TRUESIZE(0)

Fixes: 077706165717 ("virtio/vsock: don't use skbuff state to account credit")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Stefano Garzarella <sgarzare@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: "Eugenio Pérez" <eperezma@redhat.com>
Cc: virtualization@lists.linux.dev
Link: https://patch.msgid.link/20260430122653.554058-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[LL: Fixed conflict since this tree does not use buf_used added by commit
 45ca7e9f0730 ("vsock/virtio: fix `rx_bytes` accounting for stream sockets")]
Signed-off-by: Luigi Leonardi <leonardi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/vmw_vsock/virtio_transport_common.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -283,7 +283,9 @@ static int virtio_transport_send_pkt_inf
 static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
 					u32 len)
 {
-	if (vvs->rx_bytes + len > vvs->buf_alloc)
+	u64 skb_overhead = (skb_queue_len(&vvs->rx_queue) + 1) * SKB_TRUESIZE(0);
+
+	if (skb_overhead + vvs->rx_bytes + len > vvs->buf_alloc)
 		return false;
 
 	vvs->rx_bytes += len;


Patches currently in stable-queue which might be from edumazet@google.com are

queue-6.6/net-fix-icmp-host-relookup-triggering-ip_rt_bug.patch
queue-6.6/tcp-call-sk_data_ready-after-listener-migration.patch
queue-6.6/net-sched-sch_red-replace-direct-dequeue-call-with-peek-and-qdisc_dequeue_peeked.patch
queue-6.6/ip6_gre-use-cached-t-net-in-ip6erspan_changelink.patch
queue-6.6/vsock-virtio-fix-potential-unbounded-skb-queue.patch