Re: [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@xxxxxxxxxx> 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@xxxxxxxxxx>
> > ---
> >   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