Re: [Freedreno] [PATCH v2 01/10] drm/msm: fix use-after-free on probe deferral

[Kuogee Hsieh]

On 9/13/2022 1:53 AM, Johan Hovold wrote:

The bridge counter was never reset when tearing down the DRM device so
that stale pointers to deallocated structures would be accessed on the
next tear down (e.g. after a second late bind deferral).

Given enough bridges and a few probe deferrals this could currently also
lead to data beyond the bridge array being corrupted.

Fixes: d28ea556267c ("drm/msm: properly add and remove internal bridges")
Fixes: a3376e3ec81c ("drm/msm: convert to drm_bridge")
Cc: sta...@vger.kernel.org  # 3.12
Reviewed-by: Dmitry Baryshkov 
Signed-off-by: Johan Hovold 

Tested-by: Kuogee Hsieh 
Reviewed-by: Kuogee Hsieh 

---
  drivers/gpu/drm/msm/msm_drv.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 391d86b54ded..d254fe2507ec 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -241,6 +241,7 @@ static int msm_drm_uninit(struct device *dev)
  
  	for (i = 0; i < priv->num_bridges; i++)

drm_bridge_remove(priv->bridges[i]);
+   priv->num_bridges = 0;
  
  	pm_runtime_get_sync(dev);

msm_irq_uninstall(ddev);

Re: [Freedreno] [PATCH v2 01/10] drm/msm: fix use-after-free on probe deferral

[Kuogee Hsieh]

On 9/13/2022 1:53 AM, Johan Hovold wrote:

The bridge counter was never reset when tearing down the DRM device so
that stale pointers to deallocated structures would be accessed on the
next tear down (e.g. after a second late bind deferral).

Given enough bridges and a few probe deferrals this could currently also
lead to data beyond the bridge array being corrupted.

Fixes: d28ea556267c ("drm/msm: properly add and remove internal bridges")
Fixes: a3376e3ec81c ("drm/msm: convert to drm_bridge")
Cc: sta...@vger.kernel.org  # 3.12
Reviewed-by: Dmitry Baryshkov 
Signed-off-by: Johan Hovold 

Tested-by: Kuogee Hsieh 
Reviewed-by: Kuogee Hsieh 


---
  drivers/gpu/drm/msm/msm_drv.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 391d86b54ded..d254fe2507ec 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -241,6 +241,7 @@ static int msm_drm_uninit(struct device *dev)
  
  	for (i = 0; i < priv->num_bridges; i++)

drm_bridge_remove(priv->bridges[i]);
+   priv->num_bridges = 0;
  
  	pm_runtime_get_sync(dev);

msm_irq_uninstall(ddev);