CVE-2021-47097

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

Input: elantech - fix stack out of bound access in elantech_change_report_id()

The array param[] in elantech_change_report_id() must be at least 3

bytes, because elantech_read_reg_params() is calling ps2_command() with

PSMOUSE_CMD_GETINFO, that is going to access 3 bytes from param[], but

it's defined in the stack as an array of 2 bytes, therefore we have a

potential stack out-of-bounds access here, also confirmed by KASAN:

[ 6.512374] BUG: KASAN: stack-out-of-bounds in __ps2_command+0x372/0x7e0

[ 6.512397] Read of size 1 at addr ffff8881024d77c2 by task kworker/2:1/118

[ 6.512416] CPU: 2 PID: 118 Comm: kworker/2:1 Not tainted 5.13.0-22-generic #22+arighi20211110

[ 6.512428] Hardware name: LENOVO 20T8000QGE/20T8000QGE, BIOS R1AET32W (1.08 ) 08/14/2020

[ 6.512436] Workqueue: events_long serio_handle_event

[ 6.512453] Call Trace:

[ 6.512462] show_stack+0x52/0x58

[ 6.512474] dump_stack+0xa1/0

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References