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From: Chen-Yu Tsai <wenst@chromium.org>
To: Chun-Kuang Hu <chunkuang.hu@kernel.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>
Cc: Chen-Yu Tsai <wenst@chromium.org>,
	dri-devel@lists.freedesktop.org,
	linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
	Guillaume Ranquet <granquet@baylibre.com>
Subject: [PATCH v2] drm/mediatek: dp: Only trigger DRM HPD events if bridge is attached
Date: Thu,  2 Feb 2023 12:57:34 +0800	[thread overview]
Message-ID: <20230202045734.2773503-1-wenst@chromium.org> (raw)

The MediaTek DisplayPort interface bridge driver starts its interrupts
as soon as its probed. However when the interrupts trigger the bridge
might not have been attached to a DRM device. As drm_helper_hpd_irq_event()
does not check whether the passed in drm_device is valid or not, a NULL
pointer passed in results in a kernel NULL pointer dereference in it.

Check whether the bridge is attached and only trigger an HPD event if
it is.

Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Guillaume Ranquet <granquet@baylibre.com>
---
Changes since v1
- Dropped prerequisite-patch-ids
- Added Guillaume's Reviewed-by

This applies on top of mediatek-drm-next.

 drivers/gpu/drm/mediatek/mtk_dp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 1f94fcc144d3..a82f53e1a146 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1823,7 +1823,8 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
 	spin_unlock_irqrestore(&mtk_dp->irq_thread_lock, flags);
 
 	if (status & MTK_DP_THREAD_CABLE_STATE_CHG) {
-		drm_helper_hpd_irq_event(mtk_dp->bridge.dev);
+		if (mtk_dp->bridge.dev)
+			drm_helper_hpd_irq_event(mtk_dp->bridge.dev);
 
 		if (!mtk_dp->train_info.cable_plugged_in) {
 			mtk_dp_disable_sdp_aui(mtk_dp);
-- 
2.39.1.456.gfc5497dd1b-goog


WARNING: multiple messages have this Message-ID (diff)
From: Chen-Yu Tsai <wenst@chromium.org>
To: Chun-Kuang Hu <chunkuang.hu@kernel.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>
Cc: Guillaume Ranquet <granquet@baylibre.com>,
	linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	Chen-Yu Tsai <wenst@chromium.org>
Subject: [PATCH v2] drm/mediatek: dp: Only trigger DRM HPD events if bridge is attached
Date: Thu,  2 Feb 2023 12:57:34 +0800	[thread overview]
Message-ID: <20230202045734.2773503-1-wenst@chromium.org> (raw)

The MediaTek DisplayPort interface bridge driver starts its interrupts
as soon as its probed. However when the interrupts trigger the bridge
might not have been attached to a DRM device. As drm_helper_hpd_irq_event()
does not check whether the passed in drm_device is valid or not, a NULL
pointer passed in results in a kernel NULL pointer dereference in it.

Check whether the bridge is attached and only trigger an HPD event if
it is.

Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Guillaume Ranquet <granquet@baylibre.com>
---
Changes since v1
- Dropped prerequisite-patch-ids
- Added Guillaume's Reviewed-by

This applies on top of mediatek-drm-next.

 drivers/gpu/drm/mediatek/mtk_dp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 1f94fcc144d3..a82f53e1a146 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1823,7 +1823,8 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
 	spin_unlock_irqrestore(&mtk_dp->irq_thread_lock, flags);
 
 	if (status & MTK_DP_THREAD_CABLE_STATE_CHG) {
-		drm_helper_hpd_irq_event(mtk_dp->bridge.dev);
+		if (mtk_dp->bridge.dev)
+			drm_helper_hpd_irq_event(mtk_dp->bridge.dev);
 
 		if (!mtk_dp->train_info.cable_plugged_in) {
 			mtk_dp_disable_sdp_aui(mtk_dp);
-- 
2.39.1.456.gfc5497dd1b-goog


             reply	other threads:[~2023-02-02  4:58 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-02  4:57 Chen-Yu Tsai [this message]
2023-02-02  4:57 ` [PATCH v2] drm/mediatek: dp: Only trigger DRM HPD events if bridge is attached Chen-Yu Tsai
2023-02-02  9:14 ` AngeloGioacchino Del Regno
2023-02-02  9:14   ` AngeloGioacchino Del Regno
2023-02-02  9:56 ` Matthias Brugger
2023-02-02  9:56   ` Matthias Brugger
2023-03-12 15:41 ` Chun-Kuang Hu
2023-03-12 15:41   ` Chun-Kuang Hu

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