[PATCH] drm/exynos: fix a possible null-pointer dereference due to data race in exynos_drm_crtc_atomic_disable()

[Tuo Li]

Hello,

Thanks for your reply! The report is publicly available at
https://sites.google.com/view/basscheck/home. And this
patch is from the 8th report on this website.

Thanks,
Tuo Li

On Sat, Jul 1, 2023 at 4:01 PM Krzysztof Kozlowski <
krzysztof.kozlowski at linaro.org> wrote:

> On 30/06/2023 04:19, Tuo Li wrote:
> > The variable crtc->state->event is often protected by the lock
> > crtc->dev->event_lock when is accessed. However, it is accessed as a
> > condition of an if statement in exynos_drm_crtc_atomic_disable() without
> > holding the lock:
> >
> >   if (crtc->state->event && !crtc->state->active)
> >
> > However, if crtc->state->event is changed to NULL by another thread right
> > after the conditions of the if statement is checked to be true, a
> > null-pointer dereference can occur in drm_crtc_send_vblank_event():
> >
> >   e->pipe = pipe;
> >
> > To fix this possible null-pointer dereference caused by data race, the
> > spin lock coverage is extended to protect the if statement as well as
> the
> > function call to drm_crtc_send_vblank_event().
> >
> > Reported-by: BassCheck <bass at buaa.edu.cn>
>
> I cannot find this report. This is an open source work and public
> collaboration. The "Reported-by" usually means that the issue was
> reported to us, in some way, usually in public. Can we see the report?
> Otherwise adding non-public, non-verifiable reports is useless and
> clutters our report-credit-system.
>
> Best regards,
> Krzysztof
>
>
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