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SubjectRe: [PATCH v2] HID: core: Sanitize event code and type when mapping input
On Wed, 26 Aug 2020, Marc Zyngier wrote:

> When calling into hid_map_usage(), the passed event code is
> blindly stored as is, even if it doesn't fit in the associated bitmap.
>
> This event code can come from a variety of sources, including devices
> masquerading as input devices, only a bit more "programmable".
>
> Instead of taking the event code at face value, check that it actually
> fits the corresponding bitmap, and if it doesn't:
> - spit out a warning so that we know which device is acting up
> - NULLify the bitmap pointer so that we catch unexpected uses
>
> Code paths that can make use of untrusted inputs can now check
> that the mapping was indeed correct and bail out if not.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> * From v1:
> - Dropped the input.c changes, and turned hid_map_usage() into
> the validation primitive.
> - Handle mapping failures in hidinput_configure_usage() and
> mt_touch_input_mapping() (on top of hid_map_usage_clear() which
> was already handled)

Benjamin, could you please run this through your regression testing
machinery?

It's a non-trivial core change, at the same time I'd like not to postpone
it for 5.10 due to its nature.

Thanks,

--
Jiri Kosina
SUSE Labs

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