Re: [PATCH v3] HID: sensor-hub: Fail unfinished multi-value reads on removal

[Jonathan Cameron <jic23@kernel.org>]

On Sun, 13 Sep 2026 08:50:35 -0700
srinivas pandruvada <srinivas.pandruvada@linux.intel.com> wrote:

> On Sun, 2026-09-13 at 15:29 +0800, Yibo Tan wrote:
> > sensor_hub_remove() completes pending reads after stopping the HID
> > device,
> > but does not record why they completed.  A successful completion wait
> > therefore returns zero even if no complete input report was received.
> > Multi-value IIO callers then format their untouched automatic buffer
> > as a
> > successful result.
> > 
> > With a valid four-element signed 32-bit quaternion report descriptor,
> > an
> > unprivileged reader received all 16 bytes of the untouched buffer. 
> > Across
> > 11 independent KASLR-enabled boots, four reads exposed exact pointers
> > to
> > dev_rot_channels or dev_sysfs_ops.  Subtracting the matching link-
> > time
> > symbol address recovered the kernel KASLR slide in all four cases.
> > 
> > The reader ran as UID/GID 65534 with no effective capabilities
> > through the
> > mode-0644 IIO attribute.  The test used a privileged UHID broker to
> > create
> > and remove the provider; it does not demonstrate unprivileged
> > provider
> > removal.
> > 
> > Mark a pending request as shut down before completing it from the
> > removal
> > path, and return -ENODEV from a multi-value read that observes the
> > marker
> > after a successful wait.  Let removal win even if a response raced
> > with
> > teardown, since the device is no longer available.
> > 
> > The Root B-only repair returned -ENODEV with no payload or kernel
> > diagnostic in 3/3 matching signed-32-bit runs.  The source
> > reproducer,
> > complete vulnerable and fixed serial logs, result tables, and
> > checksums are
> > available in [1].
> > 
> > Link:
> > https://github.com/kimaiden1984-boop/linux-kernel-poc-collections/tree/main/cases/hid-sensor-quaternion-root-b-kaslr
> >  [1]
> > Fixes: f784fcea4506 ("HID: sensor-hub: Add
> > sensor_hub_input_attr_read_values() for multi-byte reads")
> > Cc: stable@vger.kernel.org
> > Suggested-by: Jonathan Cameron <jic23@kernel.org>
> > Assisted-by: LLM
> > Signed-off-by: Yibo Tan <lhfff@tju.edu.cn>  
> 
> 
> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>

Applied to the fixes branch of iio.git.

It might or might not go upstream before the next merge windows. In practice
I'm going to assume these devices are typically not hotplugable except in
dev kits so we are unlikely to see this on production devices unless
someone manually removes?  That does affect whether to fix it, but only how
fast we rush it upstream!

Jonathan

> 
> 
> > ---
> > Changes in v3:
> > - Replace the raw_size error sentinel with a dedicated teardown flag,
> > as
> >   suggested by Jonathan Cameron.
> > - Let teardown win if it races with a completed response.
> > 
> > v2:
> > https://lore.kernel.org/r/20260912050257.837340-1-lhfff@tju.edu.cn/
> > 
> >  drivers/hid/hid-sensor-hub.c   | 6 +++++-
> >  include/linux/hid-sensor-hub.h | 2 ++
> >  2 files changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/hid/hid-sensor-hub.c b/drivers/hid/hid-sensor-
> > hub.c
> > index 6470a290ebfc..a9bd72218c07 100644
> > --- a/drivers/hid/hid-sensor-hub.c
> > +++ b/drivers/hid/hid-sensor-hub.c
> > @@ -334,6 +334,8 @@ int sensor_hub_input_attr_read_values(struct
> > hid_sensor_hub_device *hsdev,
> >  			ret = -ETIMEDOUT;
> >  		else if (cycles < 0)
> >  			ret = cycles;
> > +		else if (hsdev->pending.shutdown)
> > +			ret = -ENODEV;
> >  
> >  		hsdev->pending.status = false;
> >  	}
> > @@ -805,8 +807,10 @@ static int sensor_hub_finalize_pending_fn(struct
> > device *dev, void *data)
> >  {
> >  	struct hid_sensor_hub_device *hsdev = dev->platform_data;
> >  
> > -	if (hsdev->pending.status)
> > +	if (hsdev->pending.status) {
> > +		hsdev->pending.shutdown = true;
> >  		complete(&hsdev->pending.ready);
> > +	}
> >  
> >  	return 0;
> >  }
> > diff --git a/include/linux/hid-sensor-hub.h b/include/linux/hid-
> > sensor-hub.h
> > index ab5cc8db3fbb..5aecf4474183 100644
> > --- a/include/linux/hid-sensor-hub.h
> > +++ b/include/linux/hid-sensor-hub.h
> > @@ -38,6 +38,7 @@ struct hid_sensor_hub_attribute_info {
> >  /**
> >   * struct sensor_hub_pending - Synchronous read pending information
> >   * @status:		Pending status true/false.
> > + * @shutdown:		The device is being removed.
> >   * @ready:		Completion synchronization data.
> >   * @usage_id:		Usage id for physical device, e.g. gyro
> > usage id.
> >   * @attr_usage_id:	Usage Id of a field, e.g. X-axis for a gyro.
> > @@ -48,6 +49,7 @@ struct hid_sensor_hub_attribute_info {
> >   */
> >  struct sensor_hub_pending {
> >  	bool status;
> > +	bool shutdown;
> >  	struct completion ready;
> >  	u32 usage_id;
> >  	u32 attr_usage_id;  
>