CVE-2026-64275: Input: elan_i2c - prevent division by zero and arithmetic underflow

From: Greg Kroah-Hartman <[email protected]>

Description
===========

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

Input: elan_i2c - prevent division by zero and arithmetic underflow

The Elan I2C touchpad driver queries the device for its physical
dimensions and trace counts to calculate the device resolution and width.
However, if the device firmware or device tree provides invalid zero
values for x_traces or y_traces, it results in a fatal division-by-zero
exception leading to a kernel panic during device probe.

Add checks to ensure these parameters are non-zero before performing
the division. If invalid trace values are detected, fall back to a safe
default of 1.

Additionally, prevent an arithmetic underflow in the touch reporting
logic. Previously, if the calculated or fallback width was smaller than
ETP_FWIDTH_REDUCE (90), the subtraction would underflow, resulting in a
massive unsigned integer being reported to userspace. Clamp the adjusted
width to a minimum of 0 to safely handle small physical dimensions and
fallback scenarios.

Completing the probe with safe fallback values ensures the sysfs nodes
are created, keeping the firmware update path intact so a recovery
firmware can be flashed to the device.

The Linux kernel CVE team has assigned CVE-2026-64275 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 3.19 with commit 6696777c6506fa52b2a0282121195843ed855be6 and fixed in 5.10.261 with commit 59d4cc5e7a9785e4bdc9c55273274c6b49d4b58d
	Issue introduced in 3.19 with commit 6696777c6506fa52b2a0282121195843ed855be6 and fixed in 5.15.212 with commit f6d10af2036d1d4a847a74fe47ebbf93bce3c84c
	Issue introduced in 3.19 with commit 6696777c6506fa52b2a0282121195843ed855be6 and fixed in 6.1.178 with commit 2f281ff0163a38fdc4cb4061f0c241e643283a5e
	Issue introduced in 3.19 with commit 6696777c6506fa52b2a0282121195843ed855be6 and fixed in 6.6.145 with commit 8c1db3418a419e788691746b9c47f863c2fd4890
	Issue introduced in 3.19 with commit 6696777c6506fa52b2a0282121195843ed855be6 and fixed in 6.12.96 with commit feb4866a42ec94764c7eb58012256f6f37664727
	Issue introduced in 3.19 with commit 6696777c6506fa52b2a0282121195843ed855be6 and fixed in 6.18.39 with commit 01e0317c256c560d8dcce2e9825eb6142ee34611
	Issue introduced in 3.19 with commit 6696777c6506fa52b2a0282121195843ed855be6 and fixed in 7.1.4 with commit 6bac57d8fe2a077b8a85b4140eeb7999078158eb
	Issue introduced in 3.19 with commit 6696777c6506fa52b2a0282121195843ed855be6 and fixed in 7.2-rc1 with commit df2b818fa009c10ff6ba875a1663ff001cda9558

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64275
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/input/mouse/elan_i2c_core.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/59d4cc5e7a9785e4bdc9c55273274c6b49d4b58d
	https://git.kernel.org/stable/c/f6d10af2036d1d4a847a74fe47ebbf93bce3c84c
	https://git.kernel.org/stable/c/2f281ff0163a38fdc4cb4061f0c241e643283a5e
	https://git.kernel.org/stable/c/8c1db3418a419e788691746b9c47f863c2fd4890
	https://git.kernel.org/stable/c/feb4866a42ec94764c7eb58012256f6f37664727
	https://git.kernel.org/stable/c/01e0317c256c560d8dcce2e9825eb6142ee34611
	https://git.kernel.org/stable/c/6bac57d8fe2a077b8a85b4140eeb7999078158eb
	https://git.kernel.org/stable/c/df2b818fa009c10ff6ba875a1663ff001cda9558