Re: [Qemu-devel] [PATCH 2/2] pci-assign: Fix potential read beyond buffer on -EBUSY

[Peter Maydell]

On 21 February 2014 16:51, Peter Maydell <address@hidden> wrote:
> On 21 February 2014 16:42, Markus Armbruster <address@hidden> wrote:
>> readlink() doesn't write a terminating null byte.
>> assign_failed_examine() passes the unterminated string to strrchr().
>> Oops.  Terminate it.
>>
>> Spotted by Coverity.
>>
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>>  hw/i386/kvm/pci-assign.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/hw/i386/kvm/pci-assign.c b/hw/i386/kvm/pci-assign.c
>> index 9686801..a825871 100644
>> --- a/hw/i386/kvm/pci-assign.c
>> +++ b/hw/i386/kvm/pci-assign.c
>> @@ -743,6 +743,7 @@ static void assign_failed_examine(AssignedDevice *dev)
>>          goto fail;
>>      }
>>
>> +    driver[r] = 0;
>
> This will write off the end of the buffer if readlink()
> filled it completely, won't it? I think you also need
> to change the readlink() 3rd argument to "sizeof(driver) - 1".

Apologies for this aspersion -- we check for
"r ==  sizeof(driver)" and bail out before we get here,
so the patch is ok.

Reviewed-by: Peter Maydell <address@hidden>

thanks
-- PMM