Commit 5f5a1318 authored by Jason Wang's avatar Jason Wang Committed by Anthony Liguori
Browse files

virtio: properly validate address before accessing config 



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 <mst@redhat.com>
Cc: Petr Matousek <pmatouse@redhat.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Acked-by: default avatarPetr Matousek <pmatouse@redhat.com>
Message-id: 1367905369-10765-1-git-send-email-jasowang@redhat.com
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 62c96360

hw/virtio/virtio.c

+18 −12
Original line number Diff line number Diff line
@@ -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);