From c3146dd39fb274ffbd70d20f8ba9e13562fb21ad Mon Sep 17 00:00:00 2001 From: Jon Maloy Date: Tue, 5 Mar 2024 16:38:49 -0500 Subject: [PATCH 3/3] virtio-net: correctly copy vnet header when flushing TX RH-Author: Jon Maloy RH-MergeRequest: 354: virtio-net: correctly copy vnet header when flushing TX RH-Jira: RHEL-19496 RH-Acked-by: Jason Wang RH-Acked-by: Stefan Hajnoczi RH-Commit: [1/1] 445b601da86a64298b776879fa0f30a4bf6c16f5 (redhat/rhel/src/qemu-kvm/jons-qemu-kvm-2) JIRA: https://issues.redhat.com/browse/RHEL-19496 CVE: CVE-2023-6693 Upstream: Merged commit 2220e8189fb94068dbad333228659fbac819abb0 Author: Jason Wang Date: Tue Jan 2 11:29:01 2024 +0800 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 Signed-off-by: Jon Maloy --- 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 f5f07f8e63..7d459726d4 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -602,6 +602,11 @@ 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) : @@ -2535,7 +2540,7 @@ 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) { @@ -2552,7 +2557,7 @@ 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); @@ -2560,8 +2565,8 @@ 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, -- 2.41.0