On 1 July 2015 at 18:37, Ilia Mirkin <imirkin@xxxxxxxxxxxx> wrote:
> On Wed, Jul 1, 2015 at 1:18 PM, Colin Ian King <colin.king@xxxxxxxxxxxxx> wrote:
>> On 01/07/15 18:12, Emil Velikov wrote:
>>> On 1 July 2015 at 17:56, Ilia Mirkin <imirkin@xxxxxxxxxxxx> wrote:
>>>> On Wed, Jul 1, 2015 at 12:51 PM, Colin King <colin.king@xxxxxxxxxxxxx> wrote:
>>>>> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>>>>>
>>>>> 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...
There is one:
drm/nouveau/nvkm/engine/disp/nv50.c: if (nvif_unpack(args->v1, 1, 1, true))
Seems like a recent addition though, I don't recall it with back when
was introduced.
-Emil
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