On 01/07/15 18:12, Emil Velikov wrote:
> On 1 July 2015 at 17:56, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> On Wed, Jul 1, 2015 at 12:51 PM, Colin King <colin.king at canonical.com>
>> wrote:
>>> From: Colin Ian King <colin.king at canonical.com>
>>>
>>> Various usif_ioctl helper functions do not initialize the
>>> return variable ret and some of the error handling return
>>> paths just return garbage values that were on the stack (or
>>> in a register). I believe that in all the cases, the
>>> initial ret variable should be set to -EINVAL and subsequent
>>> paths through these helper functions set it appropriately
>>> otherwise.
>>>
>>> Found via static analysis using cppcheck:
>>>
>>> [drivers/gpu/drm/nouveau/nouveau_usif.c:138]:
>>> (error) Uninitialized variable: ret
>>
>> It sure would seem that way, wouldn't it?
>>
>> #define nvif_unpack(d,vl,vh,m) ({
>> \
>> if ((vl) == 0 || ret == -ENOSYS) {
>> \
>> int _size = sizeof(d);
>> \
>> if (_size <= size && (d).version >= (vl) &&
>> \
>> (d).version <= (vh)) {
>> \
>> data = (u8 *)data + _size;
>> \
>> size = size - _size;
>> \
>> ret = ((m) || !size) ? 0 : -E2BIG;
>> \
>> } else {
>> \
>> ret = -ENOSYS;
>> \
>> }
>> \
>> }
>> \
>> (ret == 0);
>> \
>> })
>>
>> So actually it does get initialized, and I guess cppcheck doesn't know
>> about macros?
Hrm, what about the case when ((vl) == 0 || ret == -ENOSYS) is false,
where is ret being set in that case?
>>
> I think I'm having deja-vu, but I do recall a similar mention to Ben.
> Although in my defence I've assumed that nvif_unpack was a function,
> as macros normally are normally all caps. Seems like the patch that
> capitalises nvif_unpack never made it upstream :'-(
>
> Cheers,
> Emil
>
