Re: [Qemu-devel] [PATCH 2/2] xen-pt: fix Out-of-bounds read

[Gonglei <arei.gonglei@huawei.com>]

On 2015/2/10 14:39, Stefano Stabellini wrote:
> On Sat, 31 Jan 2015, arei.gonglei@huawei.com wrote:
>> From: Gonglei <arei.gonglei@huawei.com>
>>
>> The array length of s->real_device.io_regions[] is
>> "PCI_NUM_REGIONS - 1". Add a check, just make Coverity happy.
>>
>> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
>> ---
>>  hw/xen/xen_pt_config_init.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/hw/xen/xen_pt_config_init.c b/hw/xen/xen_pt_config_init.c
>> index 710fe50..3c8b0f1 100644
>> --- a/hw/xen/xen_pt_config_init.c
>> +++ b/hw/xen/xen_pt_config_init.c
>> @@ -443,6 +443,11 @@ static int xen_pt_bar_reg_read(XenPCIPassthroughState *s, XenPTReg *cfg_entry,
>>          return -1;
>>      }
>>  
>> +    if (index == PCI_ROM_SLOT) {
>> +        XEN_PT_ERR(&s->dev, "Internal error: Access violation at ROM BAR.\n");
>> +        return -1;
>> +    }
> 
> Could you please fix the boundaries of the check just above?
> Also please avoid using PCI_ROM_SLOT for the array index check, simply
> use PCI_NUM_REGIONS.
> 
You meaning is changing the below check:

if (index < 0 || index >= PCI_NUM_REGIONS - 1) {
        XEN_PT_ERR(&s->dev, "Internal error: Invalid BAR index [%d].\n", index);
        return -1;
    }

Isn't it?

Regards,
-Gonglei