Re: [PATCH v1] drm/nouveau/clk: avoid potential null-dereference

[Vince Hsu <vinceh@nvidia.com>]

On 01/08/2015 10:45 AM, Ilia Mirkin wrote:
> On Wed, Jan 7, 2015 at 5:29 PM, Andy Shevchenko
> <andy.shevchenko@gmail.com> wrote:
>> We have to check pointer before usage.
>>
>> Reported-by: Andrey Karpov <karpov@viva64.com>
>> Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
>> ---
>>   drivers/gpu/drm/nouveau/core/subdev/clock/base.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/nouveau/core/subdev/clock/base.c b/drivers/gpu/drm/nouveau/core/subdev/clock/base.c
>> index e51b72d..2e84436 100644
>> --- a/drivers/gpu/drm/nouveau/core/subdev/clock/base.c
>> +++ b/drivers/gpu/drm/nouveau/core/subdev/clock/base.c
>> @@ -322,7 +322,6 @@ nouveau_pstate_new(struct nouveau_clock *clk, int idx)
>>                  return 0;
>>
>>          pstate = kzalloc(sizeof(*pstate), GFP_KERNEL);
>> -       cstate = &pstate->base;
> What's wrong with this line? If pstate == NULL, &pstate->base == NULL
> as well and we return.
If pstate == NULL (kzalloc returned NULL), pstate->base triggers a null 
pointer
deference error?

Thanks,
Vince

>
>>          if (!pstate)
>>                  return -ENOMEM;
>>
>> @@ -330,6 +329,9 @@ nouveau_pstate_new(struct nouveau_clock *clk, int idx)
>>
>>          pstate->pstate = perfE.pstate;
>>          pstate->fanspeed = perfE.fanspeed;
>> +
>> +       cstate = &pstate->base;
>> +
>>          cstate->voltage = perfE.voltage;
>>          cstate->domain[nv_clk_src_core] = perfE.core;
>>          cstate->domain[nv_clk_src_shader] = perfE.shader;
>> --
>> 1.8.3.101.g727a46b
>>
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