From: Bjorn Andersson quic_bjorande@quicinc.com
[ Upstream commit a7bfb2ad2184a1fba78be35209b6019aa8cc8d4d ]
Using devres to depopulate the aux bus made sure that upon a probe deferral the EDP panel device would be destroyed and recreated upon next attempt.
But the struct device which the devres is tied to is the DPUs (drm_dev->dev), which may be happen after the DP controller is torn down.
Indications of this can be seen in the commonly seen EDID-hexdump full of zeros in the log, or the occasional/rare KASAN fault where the panel's attempt to read the EDID information causes a use after free on DP resources.
It's tempting to move the devres to the DP controller's struct device, but the resources used by the device(s) on the aux bus are explicitly torn down in the error path. The KASAN-reported use-after-free also remains, as the DP aux "module" explicitly frees its devres-allocated memory in this code path.
As such, explicitly depopulate the aux bus in the error path, and in the component unbind path, to avoid these issues.
Fixes: 2b57f726611e ("drm/msm/dp: fix aux-bus EP lifetime") Signed-off-by: Bjorn Andersson quic_bjorande@quicinc.com Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org Reviewed-by: Douglas Anderson dianders@chromium.org Patchwork: https://patchwork.freedesktop.org/patch/542163/ Link: https://lore.kernel.org/r/20230612220106.1884039-1-quic_bjorande@quicinc.com Signed-off-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/msm/dp/dp_display.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c index 3f9a18410c0bb..97776f5e12524 100644 --- a/drivers/gpu/drm/msm/dp/dp_display.c +++ b/drivers/gpu/drm/msm/dp/dp_display.c @@ -325,6 +325,8 @@ static void dp_display_unbind(struct device *dev, struct device *master,
kthread_stop(dp->ev_tsk);
+ of_dp_aux_depopulate_bus(dp->aux); + dp_power_client_deinit(dp->power); dp_unregister_audio_driver(dev, dp->audio); dp_aux_unregister(dp->aux); @@ -1538,11 +1540,6 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor) } }
-static void of_dp_aux_depopulate_bus_void(void *data) -{ - of_dp_aux_depopulate_bus(data); -} - static int dp_display_get_next_bridge(struct msm_dp *dp) { int rc; @@ -1571,12 +1568,6 @@ static int dp_display_get_next_bridge(struct msm_dp *dp) of_node_put(aux_bus); if (rc) goto error; - - rc = devm_add_action_or_reset(dp->drm_dev->dev, - of_dp_aux_depopulate_bus_void, - dp_priv->aux); - if (rc) - goto error; } else if (dp->is_edp) { DRM_ERROR("eDP aux_bus not found\n"); return -ENODEV; @@ -1601,6 +1592,7 @@ static int dp_display_get_next_bridge(struct msm_dp *dp) error: if (dp->is_edp) { disable_irq(dp_priv->irq); + of_dp_aux_depopulate_bus(dp_priv->aux); dp_display_host_phy_exit(dp_priv); dp_display_host_deinit(dp_priv); }