From 2220e8189fb94068dbad333228659fbac819abb0 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Tue, 2 Jan 2024 11:29:01 +0800 Subject: [PATCH] virtio-net: correctly copy vnet header when flushing TX When HASH_REPORT is negotiated, the guest_hdr_len might be larger than the size of the mergeable rx buffer header. Using virtio_net_hdr_mrg_rxbuf during the header swap might lead a stack overflow in this case. Fixing this by using virtio_net_hdr_v1_hash instead. Reported-by: Xiao Lei Cc: Yuri Benditovich Cc: qemu-stable@nongnu.org Cc: Mauro Matteo Cascella Fixes: CVE-2023-6693 Fixes: e22f0603fb2f ("virtio-net: reference implementation of hash report") Reviewed-by: Michael Tokarev Signed-off-by: Jason Wang Upstream-Status: Backport [https://gitlab.com/qemu-project/qemu/-/commit/2220e8189fb94068dbad333228659fbac819abb0] CVE: CVE-2023-6693 Signed-off-by: Vivek Kumbhar --- hw/net/virtio-net.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index e1f474883..42e66697f 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -600,6 +600,11 @@ static void virtio_net_set_mrg_rx_bufs(VirtIONet *n, int mergeable_rx_bufs, n->mergeable_rx_bufs = mergeable_rx_bufs; + /* + * Note: when extending the vnet header, please make sure to + * change the vnet header copying logic in virtio_net_flush_tx() + * as well. + */ if (version_1) { n->guest_hdr_len = hash_report ? sizeof(struct virtio_net_hdr_v1_hash) : @@ -2520,7 +2525,7 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) ssize_t ret; unsigned int out_num; struct iovec sg[VIRTQUEUE_MAX_SIZE], sg2[VIRTQUEUE_MAX_SIZE + 1], *out_sg; - struct virtio_net_hdr_mrg_rxbuf mhdr; + struct virtio_net_hdr_v1_hash vhdr; elem = virtqueue_pop(q->tx_vq, sizeof(VirtQueueElement)); if (!elem) { @@ -2537,7 +2542,7 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) } if (n->has_vnet_hdr) { - if (iov_to_buf(out_sg, out_num, 0, &mhdr, n->guest_hdr_len) < + if (iov_to_buf(out_sg, out_num, 0, &vhdr, n->guest_hdr_len) < n->guest_hdr_len) { virtio_error(vdev, "virtio-net header incorrect"); virtqueue_detach_element(q->tx_vq, elem, 0); @@ -2545,8 +2550,8 @@ static int32_t virtio_net_flush_tx(VirtIONetQueue *q) return -EINVAL; } if (n->needs_vnet_hdr_swap) { - virtio_net_hdr_swap(vdev, (void *) &mhdr); - sg2[0].iov_base = &mhdr; + virtio_net_hdr_swap(vdev, (void *) &vhdr); + sg2[0].iov_base = &vhdr; sg2[0].iov_len = n->guest_hdr_len; out_num = iov_copy(&sg2[1], ARRAY_SIZE(sg2) - 1, out_sg, out_num, -- 2.34.1