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From: Aleksandr Mishin <amishin@t-argos.ru>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
CC: Aleksandr Mishin <amishin@t-argos.ru>, Rob Clark <robdclark@gmail.com>,
	Abhinav Kumar <quic_abhinavk@quicinc.com>, Sean Paul <sean@poorly.run>,
	Marijn Suijten <marijn.suijten@somainline.org>, David Airlie
	<airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, Neil Armstrong
	<neil.armstrong@linaro.org>, Stephen Boyd <swboyd@chromium.org>,
	<linux-arm-msm@vger.kernel.org>, <dri-devel@lists.freedesktop.org>,
	<freedreno@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>,
	<lvc-project@linuxtesting.org>
Subject: [PATCH] drm/msm/dpu: Add callback function pointer check before its call
Date: Mon, 8 Apr 2024 11:55:23 +0300
Message-ID: <20240408085523.12231-1-amishin@t-argos.ru>
Precedence: bulk
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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.

Fixes: c929ac60b3ed ("drm/msm/dpu: allow just single IRQ callback")
Signed-off-by: Aleksandr Mishin <amishin@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);
 
-- 
2.30.2