Re: [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 <amis...@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);