| Message ID | 20200219152554.25222-1-dafna.hirschfeld@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] media: v4l2-core: fix a use-after-free bug of sd->devnode | expand |
Hi, When a subdevice is registered with v4l2_async_register_subdev_sensor_common and the main driver is unloaded and reloaded, it does not register a node for the subdevice since the devonde is not set to null. in v4l2_device_register_subdev_nodes the sd is skipped if sd->devnode. This patch solves this issue as well. Dafna On 19.02.20 16:25, Dafna Hirschfeld wrote: > sd->devnode is released after calling > v4l2_subdev_release. Therefore it should be set > to NULL so that the subdev won't hold a pointer > to a released object. This fixes a reference > after free bug in function > v4l2_device_unregister_subdev > > Cc: stable@vger.kernel.org > Fixes: 0e43734d4c46e ("media: v4l2-subdev: add release() internal op") > Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com> > Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com> > --- > changes since v2: > - since this is a regresion fix, I added Fixes and Cc to stable tags, > - change the commit title and log to be more clear. > > changes since v3: > move the sd->devnode = NULL; line below the call to the release cb > so that it can still use it. > > drivers/media/v4l2-core/v4l2-device.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/media/v4l2-core/v4l2-device.c b/drivers/media/v4l2-core/v4l2-device.c > index 63d6b147b21e..41da73ce2e98 100644 > --- a/drivers/media/v4l2-core/v4l2-device.c > +++ b/drivers/media/v4l2-core/v4l2-device.c > @@ -179,6 +179,7 @@ static void v4l2_subdev_release(struct v4l2_subdev *sd) > > if (sd->internal_ops && sd->internal_ops->release) > sd->internal_ops->release(sd); > + sd->devnode = NULL; > module_put(owner); > } > >
diff --git a/drivers/media/v4l2-core/v4l2-device.c b/drivers/media/v4l2-core/v4l2-device.c index 63d6b147b21e..41da73ce2e98 100644 --- a/drivers/media/v4l2-core/v4l2-device.c +++ b/drivers/media/v4l2-core/v4l2-device.c @@ -179,6 +179,7 @@ static void v4l2_subdev_release(struct v4l2_subdev *sd) if (sd->internal_ops && sd->internal_ops->release) sd->internal_ops->release(sd); + sd->devnode = NULL; module_put(owner); }
sd->devnode is released after calling v4l2_subdev_release. Therefore it should be set to NULL so that the subdev won't hold a pointer to a released object. This fixes a reference after free bug in function v4l2_device_unregister_subdev Cc: stable@vger.kernel.org Fixes: 0e43734d4c46e ("media: v4l2-subdev: add release() internal op") Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com> Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com> --- changes since v2: - since this is a regresion fix, I added Fixes and Cc to stable tags, - change the commit title and log to be more clear. changes since v3: move the sd->devnode = NULL; line below the call to the release cb so that it can still use it. drivers/media/v4l2-core/v4l2-device.c | 1 + 1 file changed, 1 insertion(+)