CVE-2026-64236: i2c: davinci: fix division by zero on missing clock-frequency

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

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

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

i2c: davinci: fix division by zero on missing clock-frequency

When the 'clock-frequency' property is missing from the device tree,
the driver falls back to DAVINCI_I2C_DEFAULT_BUS_FREQ. However, this
macro was defined in kHz (100), whereas the device tree property is
expected in Hz.

The probe function divided the fallback value by 1000, causing
integer truncation that resulted in dev->bus_freq = 0. This triggered
a deterministic division-by-zero kernel panic when calculating clock
dividers later in the probe sequence.

Fix this by redefining DAVINCI_I2C_DEFAULT_BUS_FREQ in Hz (100000)
to match the expected device tree property unit, allowing the existing
division logic to work correctly for both cases.

The Linux kernel CVE team has assigned CVE-2026-64236 to this issue.


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

	Issue introduced in 6.14 with commit b04ce63859793e3439b394976b8d29e785d4d69a and fixed in 6.18.35 with commit 3f43865cb64dd7cb50efae1281a95585617b12a1
	Issue introduced in 6.14 with commit b04ce63859793e3439b394976b8d29e785d4d69a and fixed in 7.0.12 with commit 9b694bc0e1831cbc5c3bbfd1b156ec719128f7d9
	Issue introduced in 6.14 with commit b04ce63859793e3439b394976b8d29e785d4d69a and fixed in 7.1 with commit 030675aa54cf757769b3db65642433d626b3ed7c

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-2026-64236
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/i2c/busses/i2c-davinci.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/3f43865cb64dd7cb50efae1281a95585617b12a1
	https://git.kernel.org/stable/c/9b694bc0e1831cbc5c3bbfd1b156ec719128f7d9
	https://git.kernel.org/stable/c/030675aa54cf757769b3db65642433d626b3ed7c