Hi, Chen-Yu: Chen-Yu Tsai <wenst@xxxxxxxxxxxx> 於 2023年2月2日 週四 下午12:57寫道： > > 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. Applied to mediatek-drm-next [1], thanks. [1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-next Regards, Chun-Kuang. > > Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver") > Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx> > Reviewed-by: Guillaume Ranquet <granquet@xxxxxxxxxxxx> > --- > 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 >
