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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 <leixiao.nop@zju.edu.cn>
Cc: Yuri Benditovich <yuri.benditovich@daynix.com>
Cc: qemu-stable@nongnu.org
Cc: Mauro Matteo Cascella <mcascell@redhat.com>
Fixes: CVE-2023-6693
Fixes: e22f0603fb ("virtio-net: reference implementation of hash report")
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Jason Wang <jasowang@redhat.com>
master
Jason Wang 2024-01-02 11:29:01 +08:00
parent 4a4efae44f
commit 2220e8189f
1 changed files with 9 additions and 4 deletions
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13
hw/net/virtio-net.c
View File

@ -674,6 +674,11 @@ 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) :
@ -2693,7 +2698,7 @@ 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) {
@ -2710,7 +2715,7 @@ 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);
@ -2718,8 +2723,8 @@ 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,