| Message ID | 20220610092924.754942-23-maxime@cerno.tech (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/vc4: Fix hotplug for vc4 | expand |
On Fri, 10 Jun 2022 at 10:30, Maxime Ripard <maxime@cerno.tech> wrote: > > 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 like 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> Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com> > --- > drivers/gpu/drm/vc4/vc4_dpi.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c > index c88e8e397730..d1eaafb43bd1 100644 > --- a/drivers/gpu/drm/vc4/vc4_dpi.c > +++ b/drivers/gpu/drm/vc4/vc4_dpi.c > @@ -244,9 +244,10 @@ static int vc4_dpi_bind(struct device *dev, struct device *master, void *data) > struct vc4_dpi *dpi; > int ret; > > - dpi = devm_kzalloc(dev, sizeof(*dpi), GFP_KERNEL); > + dpi = drmm_kzalloc(drm, sizeof(*dpi), GFP_KERNEL); > if (!dpi) > return -ENOMEM; > + > dpi->encoder.type = VC4_ENCODER_TYPE_DPI; > dpi->pdev = pdev; > dpi->regs = vc4_ioremap_regs(pdev, 0); > -- > 2.36.1 >
diff --git a/drivers/gpu/drm/vc4/vc4_dpi.c b/drivers/gpu/drm/vc4/vc4_dpi.c index c88e8e397730..d1eaafb43bd1 100644 --- a/drivers/gpu/drm/vc4/vc4_dpi.c +++ b/drivers/gpu/drm/vc4/vc4_dpi.c @@ -244,9 +244,10 @@ static int vc4_dpi_bind(struct device *dev, struct device *master, void *data) struct vc4_dpi *dpi; int ret; - dpi = devm_kzalloc(dev, sizeof(*dpi), GFP_KERNEL); + dpi = drmm_kzalloc(drm, sizeof(*dpi), GFP_KERNEL); if (!dpi) return -ENOMEM; + dpi->encoder.type = VC4_ENCODER_TYPE_DPI; dpi->pdev = pdev; dpi->regs = vc4_ioremap_regs(pdev, 0);
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 like 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_dpi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)