Our internal structure that stores the DRM entities structure is allocated through a device-managed kzalloc.
This means that this will eventually be freed whenever the device is removed. In our case, the most likely source of removal is that the main device is going to be unbound, and component_unbind_all() is being run.
However, it occurs while the DRM device is still registered, which will create dangling pointers, eventually resulting in use-after-free.
Switch to a DRM-managed allocation to keep our structure until the DRM driver doesn't need it anymore.
Signed-off-by: Maxime Ripard maxime@cerno.tech --- drivers/gpu/drm/vc4/vc4_hdmi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 823d812f4982..fd7bfcd1696f 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -2834,9 +2834,10 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data) struct device_node *ddc_node; int ret;
- vc4_hdmi = devm_kzalloc(dev, sizeof(*vc4_hdmi), GFP_KERNEL); + vc4_hdmi = drmm_kzalloc(drm, sizeof(*vc4_hdmi), GFP_KERNEL); if (!vc4_hdmi) return -ENOMEM; + mutex_init(&vc4_hdmi->mutex); spin_lock_init(&vc4_hdmi->hw_lock); INIT_DELAYED_WORK(&vc4_hdmi->scrambling_work, vc4_hdmi_scrambling_wq);