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

[Abhinav Kumar]

On 4/8/2024 1:55 AM, Aleksandr Mishin 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.
> 

Yes , as dmitry wrote, this should be Reported-by.

But rest LGTM.

> 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);
>