From: Tuo Li <islituo@gmail.com>
To: inki.dae@samsung.com, sw0312.kim@samsung.com,
kyungmin.park@samsung.com, airlied@gmail.com, daniel@ffwll.ch,
krzysztof.kozlowski@linaro.org, alim.akhtar@samsung.com
Cc: dri-devel@lists.freedesktop.org,
linux-arm-kernel@lists.infradead.org,
linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
baijiaju1990@outlook.com, Tuo Li <islituo@gmail.com>,
BassCheck <bass@buaa.edu.cn>
Subject: [PATCH] drm/exynos: fix a possible null-pointer dereference due to data race in exynos_drm_crtc_atomic_disable()
Date: Fri, 30 Jun 2023 10:19:06 +0800 [thread overview]
Message-ID: <20230630021906.1035115-1-islituo@gmail.com> (raw)
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@buaa.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
---
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,
--
2.34.1
next reply other threads:[~2023-06-30 2:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20230630022033epcas1p2a104f08061a51a240364b72eb43842d8@epcas1p2.samsung.com>
2023-06-30 2:19 ` Tuo Li [this message]
2023-07-01 8:01 ` [PATCH] drm/exynos: fix a possible null-pointer dereference due to data race in exynos_drm_crtc_atomic_disable() Krzysztof Kozlowski
[not found] ` <CADm8Ten-1yBdQFaETvS19j=_UFC4GEJqH38DU=7xPXLkOnvvzg@mail.gmail.com>
2023-07-04 7:27 ` Krzysztof Kozlowski
2023-07-04 7:35 ` Krzysztof Kozlowski
2023-07-13 0:32 ` 대인기/Tizen Platform Lab(SR)/삼성전자
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