This is a note to let you know that I've just added the patch titled
drm/mediatek: dp: Only trigger DRM HPD events if bridge is attached
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-mediatek-dp-only-trigger-drm-hpd-events-if-bridg.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit db2d8f8594f3e9ae62d9d4dc2cb9decad18cbc5b
Author: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>
Date: Thu Feb 2 12:57:34 2023 +0800
drm/mediatek: dp: Only trigger DRM HPD events if bridge is attached
[ Upstream commit 36b617f7e4ae663fcadd202ea061ca695ca75539 ]
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@xxxxxxxxxxxx>
Reviewed-by: Guillaume Ranquet <granquet@xxxxxxxxxxxx>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Reviewed-by: Matthias Brugger <matthias.bgg@xxxxxxxxx>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20230202045734.2773503-1-wenst@xxxxxxxxxxxx/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 9d085c05c49c3..d28326350ea93 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);
