CVE-2026-64270: Input: mms114 - reject an oversized device packet size

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

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

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

Input: mms114 - reject an oversized device packet size

mms114_interrupt() reads a packet of touch data from the device into a
fixed-size on-stack buffer

	struct mms114_touch touch[MMS114_MAX_TOUCH];

which holds MMS114_MAX_TOUCH (10) events of MMS114_EVENT_SIZE (8) bytes,
i.e. 80 bytes. The length of the I2C read into it is taken verbatim from
the device:

	packet_size = mms114_read_reg(data, MMS114_PACKET_SIZE);
	if (packet_size <= 0)
		goto out;
	...
	error = __mms114_read_reg(data, MMS114_INFORMATION, packet_size,
			(u8 *)touch);

packet_size is a single device register byte (0x0F) and the only check
is the lower bound packet_size <= 0; it is never bounded against the
size of touch[]. A malfunctioning, malicious or counterfeit controller
(or an attacker tampering with the I2C bus) can report a packet_size of
up to 255, so __mms114_read_reg() writes up to 175 bytes past the end of
touch[] on the IRQ-thread stack: a stack out-of-bounds write that can
overwrite the stack canary, saved registers and the return address.

A well-formed device never reports more than the buffer holds, so reject
an oversized packet and drop the report, consistent with the handler's
other error paths, rather than reading past the buffer.

The Linux kernel CVE team has assigned CVE-2026-64270 to this issue.


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

	Issue introduced in 3.6 with commit 07b8481d4aff73d6f451f25e74ea10240ff5131e and fixed in 6.6.145 with commit 5d2ea15ba03bf17ed143ff1a0995a4206edc3fb6
	Issue introduced in 3.6 with commit 07b8481d4aff73d6f451f25e74ea10240ff5131e and fixed in 6.12.96 with commit b78150729762d47c14fe29a2582bdca5568e62b8
	Issue introduced in 3.6 with commit 07b8481d4aff73d6f451f25e74ea10240ff5131e and fixed in 6.18.39 with commit 8301c335305344d4da4ab9442b6a399dacfe5b8d
	Issue introduced in 3.6 with commit 07b8481d4aff73d6f451f25e74ea10240ff5131e and fixed in 7.1.4 with commit f3d5e77b27fded71dcb97f409262bf0abba0410e
	Issue introduced in 3.6 with commit 07b8481d4aff73d6f451f25e74ea10240ff5131e and fixed in 7.2-rc1 with commit 66725039f7090afe14c31bd259e2059a68f04023

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-2026-64270
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/touchscreen/mms114.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/5d2ea15ba03bf17ed143ff1a0995a4206edc3fb6
	https://git.kernel.org/stable/c/b78150729762d47c14fe29a2582bdca5568e62b8
	https://git.kernel.org/stable/c/8301c335305344d4da4ab9442b6a399dacfe5b8d
	https://git.kernel.org/stable/c/f3d5e77b27fded71dcb97f409262bf0abba0410e
	https://git.kernel.org/stable/c/66725039f7090afe14c31bd259e2059a68f04023