[PATCH] drm/msm/dpu: Add callback function pointer check before its call

[Aleksandr Mishin]

On 08.04.2024 12:03, Dmitry Baryshkov wrote:
> On Mon, 8 Apr 2024 at 11:57, Aleksandr Mishin <amishin at t-argos.ru> wrote:
>>
>> In dpu_core_irq_callback_handler() callback function pointer is compared to NULL,
>> but then callback function is unconditionally called by this pointer.
>> Fix this bug by adding conditional return.
>>
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> This should be converted to a proper Reported-by: trailer.
> 

It is an established practice for our project, you can find 700+ applied
patches with similar line:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?qt=grep&q=linuxtesting.org

>>
>> Fixes: c929ac60b3ed ("drm/msm/dpu: allow just single IRQ callback")
>> Signed-off-by: Aleksandr Mishin <amishin at t-argos.ru>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> index 946dd0135dff..03a16fbd4c99 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> @@ -223,9 +223,11 @@ static void dpu_core_irq_callback_handler(struct dpu_kms *dpu_kms, unsigned int
>>
>>          VERB("IRQ=[%d, %d]\n", DPU_IRQ_REG(irq_idx), DPU_IRQ_BIT(irq_idx));
>>
>> -       if (!irq_entry->cb)
>> +       if (!irq_entry->cb) {
>>                  DRM_ERROR("no registered cb, IRQ=[%d, %d]\n",
>>                            DPU_IRQ_REG(irq_idx), DPU_IRQ_BIT(irq_idx));
>> +               return;
>> +       }
>>
>>          atomic_inc(&irq_entry->count);
>>
>> --
>> 2.30.2
>>
>>
> 
> 

-- 
Kind regards
Aleksandr