From 2e63972a2de14482d0eae1a03a73e379f1c3f44c Mon Sep 17 00:00:00 2001 From: Tuo Li Date: Fri, 30 Jun 2023 10:19:06 +0800 Subject: [PATCH 1/2] drm/exynos: fix a possible null-pointer dereference due to data race in exynos_drm_crtc_atomic_disable() 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 Link: https://sites.google.com/view/basscheck/home Signed-off-by: Tuo Li Reviewed-by: Krzysztof Kozlowski Added relevant link. Signed-off-by: Inki Dae --- drivers/gpu/drm/exynos/exynos_drm_crtc.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/exynos/exynos_drm_crtc.c b/drivers/gpu/drm/exynos/exynos_drm_crtc.c index 4153f302de7c..d19e796c2061 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_crtc.c +++ b/drivers/gpu/drm/exynos/exynos_drm_crtc.c @@ -39,13 +39,12 @@ static void exynos_drm_crtc_atomic_disable(struct drm_crtc *crtc, if (exynos_crtc->ops->atomic_disable) exynos_crtc->ops->atomic_disable(exynos_crtc); + spin_lock_irq(&crtc->dev->event_lock); if (crtc->state->event && !crtc->state->active) { - spin_lock_irq(&crtc->dev->event_lock); drm_crtc_send_vblank_event(crtc, crtc->state->event); - spin_unlock_irq(&crtc->dev->event_lock); - crtc->state->event = NULL; } + spin_unlock_irq(&crtc->dev->event_lock); } static int exynos_crtc_atomic_check(struct drm_crtc *crtc, From 6b83c85b64078ff49b4d3d0b2cd2c2bf6f1b6a85 Mon Sep 17 00:00:00 2001 From: Zhu Wang Date: Mon, 31 Jul 2023 20:33:36 +0800 Subject: [PATCH 2/2] drm/exynos: remove redundant of_match_ptr The driver depends on CONFIG_OF, so it is not necessary to use of_match_ptr here. Even for drivers that do not depend on CONFIG_OF, it's almost always better to leave out the of_match_ptr(), since the only thing it can possibly do is to save a few bytes of .text if a driver can be used both with and without it. Hence we remove of_match_ptr. Signed-off-by: Zhu Wang Reviewed-by: Krzysztof Kozlowski Signed-off-by: Inki Dae --- drivers/gpu/drm/exynos/exynos_drm_gsc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/exynos/exynos_drm_gsc.c b/drivers/gpu/drm/exynos/exynos_drm_gsc.c index 964dceb28c1e..34cdabc30b4f 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_gsc.c +++ b/drivers/gpu/drm/exynos/exynos_drm_gsc.c @@ -1426,6 +1426,6 @@ struct platform_driver gsc_driver = { .name = "exynos-drm-gsc", .owner = THIS_MODULE, .pm = &gsc_pm_ops, - .of_match_table = of_match_ptr(exynos_drm_gsc_of_match), + .of_match_table = exynos_drm_gsc_of_match, }, };