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[Qemu-devel] [PATCH V2] virtio: properly validate address before accessi
From: |
Jason Wang |
Subject: |
[Qemu-devel] [PATCH V2] virtio: properly validate address before accessing config |
Date: |
Tue, 7 May 2013 13:42:49 +0800 |
There are several several issues in the current checking:
- The check was based on the minus of unsigned values which can overflow
- It was done after .{set|get}_config() which can lead crash when config_len
is zero since vdev->config is NULL
Fix this by:
- Validate the address in virtio_pci_config_{read|write}() before
.{set|get}_config
- Use addition instead minus to do the validation
Cc: Michael S. Tsirkin <address@hidden>
Cc: Petr Matousek <address@hidden>
Signed-off-by: Jason Wang <address@hidden>
---
Changes from V1:
- Doing check in virtio.c instead of virtio-pci.c
- Drop the patch of virtio-ccw and s390-virtio-bus
---
hw/virtio/virtio.c | 30 ++++++++++++++++++------------
1 files changed, 18 insertions(+), 12 deletions(-)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 53a0d90..8176c14 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -568,10 +568,11 @@ uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t
addr)
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint8_t val;
- k->get_config(vdev, vdev->config);
-
- if (addr > (vdev->config_len - sizeof(val)))
+ if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
+ }
+
+ k->get_config(vdev, vdev->config);
val = ldub_p(vdev->config + addr);
return val;
@@ -582,10 +583,11 @@ uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t
addr)
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint16_t val;
- k->get_config(vdev, vdev->config);
-
- if (addr > (vdev->config_len - sizeof(val)))
+ if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
+ }
+
+ k->get_config(vdev, vdev->config);
val = lduw_p(vdev->config + addr);
return val;
@@ -596,10 +598,11 @@ uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t
addr)
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint32_t val;
- k->get_config(vdev, vdev->config);
-
- if (addr > (vdev->config_len - sizeof(val)))
+ if (addr + sizeof(val) > vdev->config_len) {
return (uint32_t)-1;
+ }
+
+ k->get_config(vdev, vdev->config);
val = ldl_p(vdev->config + addr);
return val;
@@ -610,8 +613,9 @@ void virtio_config_writeb(VirtIODevice *vdev, uint32_t
addr, uint32_t data)
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint8_t val = data;
- if (addr > (vdev->config_len - sizeof(val)))
+ if (addr + sizeof(val) > vdev->config_len) {
return;
+ }
stb_p(vdev->config + addr, val);
@@ -625,8 +629,9 @@ void virtio_config_writew(VirtIODevice *vdev, uint32_t
addr, uint32_t data)
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint16_t val = data;
- if (addr > (vdev->config_len - sizeof(val)))
+ if (addr + sizeof(val) > vdev->config_len) {
return;
+ }
stw_p(vdev->config + addr, val);
@@ -640,8 +645,9 @@ void virtio_config_writel(VirtIODevice *vdev, uint32_t
addr, uint32_t data)
VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
uint32_t val = data;
- if (addr > (vdev->config_len - sizeof(val)))
+ if (addr + sizeof(val) > vdev->config_len) {
return;
+ }
stl_p(vdev->config + addr, val);
--
1.7.1
- [Qemu-devel] [PATCH V2] virtio: properly validate address before accessing config,
Jason Wang <=