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?
>
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
