From: Chen-Yu Tsai wenst@chromium.org
[ 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@chromium.org Reviewed-by: Guillaume Ranquet granquet@baylibre.com Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com Reviewed-by: Matthias Brugger matthias.bgg@gmail.com Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20230202045734.277... Signed-off-by: Chun-Kuang Hu chunkuang.hu@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 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);