HID: core: Sanitize event code and type when mapping input
authorMarc Zyngier <maz@kernel.org>
Tue, 1 Sep 2020 09:52:33 +0000 (10:52 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 12 Sep 2020 09:47:31 +0000 (11:47 +0200)
commitac48d8300edd1aa4ce0fbef0ff5136d363f44cdf
tree0995722c4408ed6dcbef261ca0fd8ebf4378f58d
parentcf7797ea60e3e721e3ae5090edbc2ec72d715436
HID: core: Sanitize event code and type when mapping input

commit 35556bed836f8dc07ac55f69c8d17dce3e7f0e25 upstream.

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>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/hid/hid-input.c
drivers/hid/hid-multitouch.c
include/linux/hid.h