137 lines
4.5 KiB
Diff
137 lines
4.5 KiB
Diff
From c21488ecfff60d0acd0e8ced19f94b3ac050f945 Mon Sep 17 00:00:00 2001
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From: Jason Wang <jasowang@redhat.com>
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Date: Thu, 2 Sep 2021 13:44:12 +0800
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Subject: [PATCH] virtio-net: fix use after unmap/free for sg
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Jon Maloy <jmaloy@redhat.com>
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RH-MergeRequest: 45: virtio-net: fix use after unmap/free for sg
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RH-Commit: [1/1] 85cd1f4894f9584a11b797303139be479ce9781d (jmaloy/qemu-kvm)
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RH-Bugzilla: 1999221
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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When mergeable buffer is enabled, we try to set the num_buffers after
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the virtqueue elem has been unmapped. This will lead several issues,
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E.g a use after free when the descriptor has an address which belongs
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to the non direct access region. In this case we use bounce buffer
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that is allocated during address_space_map() and freed during
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address_space_unmap().
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Fixing this by storing the elems temporarily in an array and delay the
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unmap after we set the the num_buffers.
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This addresses CVE-2021-3748.
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Reported-by: Alexander Bulekov <alxndr@bu.edu>
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Fixes: fbe78f4f55c6 ("virtio-net support")
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Jason Wang <jasowang@redhat.com>
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(cherry picked from commit bedd7e93d01961fcb16a97ae45d93acf357e11f6)
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Signed-off-by: Jon Maloy <jmaloy@redhat.com>
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---
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hw/net/virtio-net.c | 39 ++++++++++++++++++++++++++++++++-------
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1 file changed, 32 insertions(+), 7 deletions(-)
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diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
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index 16d20cdee5..f205331dcf 100644
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--- a/hw/net/virtio-net.c
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+++ b/hw/net/virtio-net.c
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@@ -1746,10 +1746,13 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
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VirtIONet *n = qemu_get_nic_opaque(nc);
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VirtIONetQueue *q = virtio_net_get_subqueue(nc);
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VirtIODevice *vdev = VIRTIO_DEVICE(n);
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+ VirtQueueElement *elems[VIRTQUEUE_MAX_SIZE];
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+ size_t lens[VIRTQUEUE_MAX_SIZE];
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struct iovec mhdr_sg[VIRTQUEUE_MAX_SIZE];
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struct virtio_net_hdr_mrg_rxbuf mhdr;
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unsigned mhdr_cnt = 0;
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- size_t offset, i, guest_offset;
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+ size_t offset, i, guest_offset, j;
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+ ssize_t err;
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if (!virtio_net_can_receive(nc)) {
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return -1;
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@@ -1780,6 +1783,12 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
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total = 0;
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+ if (i == VIRTQUEUE_MAX_SIZE) {
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+ virtio_error(vdev, "virtio-net unexpected long buffer chain");
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+ err = size;
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+ goto err;
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+ }
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+
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elem = virtqueue_pop(q->rx_vq, sizeof(VirtQueueElement));
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if (!elem) {
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if (i) {
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@@ -1791,7 +1800,8 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
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n->guest_hdr_len, n->host_hdr_len,
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vdev->guest_features);
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}
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- return -1;
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+ err = -1;
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+ goto err;
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}
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if (elem->in_num < 1) {
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@@ -1799,7 +1809,8 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
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"virtio-net receive queue contains no in buffers");
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virtqueue_detach_element(q->rx_vq, elem, 0);
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g_free(elem);
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- return -1;
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+ err = -1;
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+ goto err;
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}
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sg = elem->in_sg;
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@@ -1836,12 +1847,13 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
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if (!n->mergeable_rx_bufs && offset < size) {
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virtqueue_unpop(q->rx_vq, elem, total);
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g_free(elem);
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- return size;
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+ err = size;
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+ goto err;
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}
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- /* signal other side */
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- virtqueue_fill(q->rx_vq, elem, total, i++);
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- g_free(elem);
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+ elems[i] = elem;
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+ lens[i] = total;
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+ i++;
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}
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if (mhdr_cnt) {
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@@ -1851,10 +1863,23 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
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&mhdr.num_buffers, sizeof mhdr.num_buffers);
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}
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+ for (j = 0; j < i; j++) {
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+ /* signal other side */
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+ virtqueue_fill(q->rx_vq, elems[j], lens[j], j);
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+ g_free(elems[j]);
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+ }
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+
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virtqueue_flush(q->rx_vq, i);
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virtio_notify(vdev, q->rx_vq);
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return size;
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+
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+err:
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+ for (j = 0; j < i; j++) {
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+ g_free(elems[j]);
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+ }
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+
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+ return err;
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}
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static ssize_t virtio_net_do_receive(NetClientState *nc, const uint8_t *buf,
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--
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2.18.2
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