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Re: [Qemu-devel] [PATCH 1/3] virtio-pci: properly validate address befor
From: |
Jason Wang |
Subject: |
Re: [Qemu-devel] [PATCH 1/3] virtio-pci: properly validate address before accessing config |
Date: |
Sun, 28 Apr 2013 15:54:20 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130404 Thunderbird/17.0.5 |
On 04/28/2013 03:26 AM, Michael S. Tsirkin wrote:
> On Fri, Apr 26, 2013 at 04:34:02PM +0800, Jason Wang wrote:
>> 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>
> Why do this in virtio-pci and not in virtio.c?
> If instead we correct the checks in virtio.c we
> get less code, and all transports will benefit
> automatically.
I wish I could but looks like vitio_config_read{b|w|l} were only used by
virtio-pci. Other transport such as ccw and s390-virtio-bus have their
own implementation.
>
>> ---
>> hw/virtio/virtio-pci.c | 9 +++++++++
>> hw/virtio/virtio.c | 18 ------------------
>> 2 files changed, 9 insertions(+), 18 deletions(-)
>>
>> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
>> index a1f15a8..7f6c7d1 100644
>> --- a/hw/virtio/virtio-pci.c
>> +++ b/hw/virtio/virtio-pci.c
>> @@ -400,6 +400,10 @@ static uint64_t virtio_pci_config_read(void *opaque,
>> hwaddr addr,
>> }
>> addr -= config;
>>
>> + if (addr + size > proxy->vdev->config_len) {
>> + return (uint32_t)-1;
>> + }
>> +
>> switch (size) {
>> case 1:
>> val = virtio_config_readb(proxy->vdev, addr);
>> @@ -430,6 +434,11 @@ static void virtio_pci_config_write(void *opaque,
>> hwaddr addr,
>> return;
>> }
>> addr -= config;
>> +
>> + if (addr + size > proxy->vdev->config_len) {
>> + return;
>> + }
>> +
>> /*
>> * Virtio-PCI is odd. Ioports are LE but config space is target native
>> * endian.
>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>> index 1c2282c..3397b5e 100644
>> --- a/hw/virtio/virtio.c
>> +++ b/hw/virtio/virtio.c
>> @@ -563,9 +563,6 @@ uint32_t virtio_config_readb(VirtIODevice *vdev,
>> uint32_t addr)
>>
>> vdev->get_config(vdev, vdev->config);
>>
>> - if (addr > (vdev->config_len - sizeof(val)))
>> - return (uint32_t)-1;
>> -
>> val = ldub_p(vdev->config + addr);
>> return val;
>> }
>> @@ -576,9 +573,6 @@ uint32_t virtio_config_readw(VirtIODevice *vdev,
>> uint32_t addr)
>>
>> vdev->get_config(vdev, vdev->config);
>>
>> - if (addr > (vdev->config_len - sizeof(val)))
>> - return (uint32_t)-1;
>> -
>> val = lduw_p(vdev->config + addr);
>> return val;
>> }
>> @@ -589,9 +583,6 @@ uint32_t virtio_config_readl(VirtIODevice *vdev,
>> uint32_t addr)
>>
>> vdev->get_config(vdev, vdev->config);
>>
>> - if (addr > (vdev->config_len - sizeof(val)))
>> - return (uint32_t)-1;
>> -
>> val = ldl_p(vdev->config + addr);
>> return val;
>> }
>> @@ -600,9 +591,6 @@ void virtio_config_writeb(VirtIODevice *vdev, uint32_t
>> addr, uint32_t data)
>> {
>> uint8_t val = data;
>>
>> - if (addr > (vdev->config_len - sizeof(val)))
>> - return;
>> -
>> stb_p(vdev->config + addr, val);
>>
>> if (vdev->set_config)
>> @@ -613,9 +601,6 @@ void virtio_config_writew(VirtIODevice *vdev, uint32_t
>> addr, uint32_t data)
>> {
>> uint16_t val = data;
>>
>> - if (addr > (vdev->config_len - sizeof(val)))
>> - return;
>> -
>> stw_p(vdev->config + addr, val);
>>
>> if (vdev->set_config)
>> @@ -626,9 +611,6 @@ void virtio_config_writel(VirtIODevice *vdev, uint32_t
>> addr, uint32_t data)
>> {
>> uint32_t val = data;
>>
>> - if (addr > (vdev->config_len - sizeof(val)))
>> - return;
>> -
>> stl_p(vdev->config + addr, val);
>>
>> if (vdev->set_config)
>> --
>> 1.7.1
- Re: [Qemu-devel] [PATCH 2/3] virtio-ccw: check config length before accessing it, (continued)