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[80.230.48.7]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45da0fe1a41sm16563554f8f.31.2026.05.15.08.31.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 May 2026 08:31:52 -0700 (PDT) Date: Fri, 15 May 2026 11:31:49 -0400 From: "Michael S. Tsirkin" To: Luigi Leonardi Cc: stable@vger.kernel.org, Stefano Garzarella , Eric Dumazet , Arseniy Krasnov , Stefan Hajnoczi , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , virtualization@lists.linux.dev, Jakub Kicinski Subject: Re: [PATCH] vsock/virtio: fix potential unbounded skb queue Message-ID: <20260515113100-mutt-send-email-mst@kernel.org> References: <20260515-dumazet-v1-1-73468c902889@redhat.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260515-dumazet-v1-1-73468c902889@redhat.com> On Fri, May 15, 2026 at 04:22:12PM +0200, Luigi Leonardi wrote: > From: Eric Dumazet > > Upstream commit 059b7dbd20a6f0c539a45ddff1573cb8946685b5 > > 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 > Cc: Arseniy Krasnov > Cc: Stefan Hajnoczi > Cc: Stefano Garzarella > Cc: Michael S. Tsirkin > Cc: Jason Wang > Cc: Xuan Zhuo > Cc: Eugenio Pérez > Cc: virtualization@lists.linux.dev > Link: https://patch.msgid.link/20260430122653.554058-1-edumazet@google.com > Signed-off-by: Jakub Kicinski > [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 > --- > net/vmw_vsock/virtio_transport_common.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > index 4c374c36c29d..86e3051d000e 100644 > --- 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_info(struct vsock_sock *vsk, > 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; > > --- > base-commit: 3b9f64db049687c0d38b4b3ef2f297f0642179af > change-id: 20260515-dumazet-07c0c855a9e2 > > Best regards, > -- > Luigi Leonardi I am not sure we should queue this for stable yet. It causes regressions that we are now trying to fix. -- MST