On Wed, Jul 1, 2015 at 1:18 PM, Colin Ian King <colin.king at canonical.com>
wrote:
> 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?
Is that actually the case for any of the callsites? gcc would complain
about that...
