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[Qemu-devel] [PATCH 8/9] virtio-serial: Handle scatter-gather buffers fo
From: |
Amit Shah |
Subject: |
[Qemu-devel] [PATCH 8/9] virtio-serial: Handle scatter-gather buffers for control messages |
Date: |
Tue, 23 Mar 2010 20:00:18 +0530 |
Current control messages are small enough to not be split into multiple
buffers but we could run into such a situation in the future or a
malicious guest could cause such a situation.
So handle the entire iov request for control messages.
Also ensure the size of the control request is >= what we expect
otherwise we risk accessing memory that we don't own.
Signed-off-by: Amit Shah <address@hidden>
CC: Avi Kivity <address@hidden>
Reported-by: Avi Kivity <address@hidden>
---
hw/virtio-serial-bus.c | 44 +++++++++++++++++++++++++++++++++++++++++---
1 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index 6d12c10..fe976ec 100644
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -205,7 +205,7 @@ size_t virtio_serial_guest_ready(VirtIOSerialPort *port)
}
/* Guest wants to notify us of some event */
-static void handle_control_message(VirtIOSerial *vser, void *buf)
+static void handle_control_message(VirtIOSerial *vser, void *buf, size_t len)
{
struct VirtIOSerialPort *port;
struct virtio_console_control cpkt, *gcpkt;
@@ -214,6 +214,11 @@ static void handle_control_message(VirtIOSerial *vser,
void *buf)
gcpkt = buf;
+ if (len < sizeof(cpkt)) {
+ /* The guest sent an invalid control packet */
+ return;
+ }
+
cpkt.event = lduw_p(&gcpkt->event);
cpkt.value = lduw_p(&gcpkt->value);
@@ -297,12 +302,45 @@ static void control_out(VirtIODevice *vdev, VirtQueue *vq)
{
VirtQueueElement elem;
VirtIOSerial *vser;
+ uint8_t *buf;
+ size_t len;
vser = DO_UPCAST(VirtIOSerial, vdev, vdev);
+ len = 0;
+ buf = NULL;
while (virtqueue_pop(vq, &elem)) {
- handle_control_message(vser, elem.out_sg[0].iov_base);
- virtqueue_push(vq, &elem, elem.out_sg[0].iov_len);
+ unsigned int i;
+ size_t cur_len, offset;
+
+ cur_len = 0;
+ for (i = 0; i < elem.out_num; i++) {
+ cur_len += elem.out_sg[i].iov_len;
+ }
+ /*
+ * Allocate a new buf only if we didn't have one previously or
+ * if the size of the buf differs
+ */
+ if (cur_len != len) {
+ if (len) {
+ qemu_free(buf);
+ }
+ buf = qemu_malloc(cur_len);
+ }
+
+ offset = 0;
+ for (i = 0; i < elem.out_num; i++) {
+ memcpy(buf + offset, elem.out_sg[i].iov_base,
+ elem.out_sg[i].iov_len);
+ offset += elem.out_sg[i].iov_len;
+ }
+ len = cur_len;
+
+ handle_control_message(vser, buf, len);
+ virtqueue_push(vq, &elem, len);
+ }
+ if (len) {
+ qemu_free(buf);
}
virtio_notify(vdev, vq);
}
--
1.6.2.5
- [Qemu-devel] [PATCH 0/9] v2: Fixes, new way of discovering ports, Amit Shah, 2010/03/23
- [Qemu-devel] [PATCH 1/9] virtio-serial-bus: save/load: Ensure target has enough ports, Amit Shah, 2010/03/23
- [Qemu-devel] [PATCH 2/9] virtio-serial-bus: save/load: Ensure nr_ports on src and dest are same., Amit Shah, 2010/03/23
- [Qemu-devel] [PATCH 3/9] virtio-serial: Remove redundant check for 0-sized write request, Amit Shah, 2010/03/23
- [Qemu-devel] [PATCH 4/9] virtio-serial: Update copyright year to 2010, Amit Shah, 2010/03/23
- [Qemu-devel] [PATCH 5/9] virtio-serial: save/load: Ensure we have hot-plugged ports instantiated, Amit Shah, 2010/03/23
- [Qemu-devel] [PATCH 6/9] virtio-serial-bus: Use control messages to notify guest of new ports, Amit Shah, 2010/03/23
- [Qemu-devel] [PATCH 7/9] virtio-serial-bus: Let the guest know of host connection changes after migration, Amit Shah, 2010/03/23
- [Qemu-devel] [PATCH 8/9] virtio-serial: Handle scatter-gather buffers for control messages,
Amit Shah <=
- [Qemu-devel] [PATCH 9/9] virtio-serial: Handle scatter/gather input from the guest, Amit Shah, 2010/03/23
- [Qemu-devel] Re: [PATCH 9/9] virtio-serial: Handle scatter/gather input from the guest, Amit Shah, 2010/03/23
[Qemu-devel] Re: [PATCH 0/9] v2: Fixes, new way of discovering ports, Juan Quintela, 2010/03/23