CVE-2026-64169: spi: ep93xx: fix error pointer deref after DMA setup failure

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

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

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

spi: ep93xx: fix error pointer deref after DMA setup failure

The driver falls back to PIO mode if DMA setup fails during probe.

Make sure to the clear the DMA channel pointers on setup failure to
avoid dereferencing an error pointer on later probe errors or driver
unbind.

This issue was flagged by Sashiko when reviewing a devres allocation
conversion patch.

The Linux kernel CVE team has assigned CVE-2026-64169 to this issue.


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

	Issue introduced in 6.12 with commit e79e7c2df6277ee1ad9364a231f6183da4492415 and fixed in 6.12.92 with commit b6c0dabea07e25bd7db19a77ebfd0d02b9e2671a
	Issue introduced in 6.12 with commit e79e7c2df6277ee1ad9364a231f6183da4492415 and fixed in 6.18.34 with commit 8e027db9fa310b1d5e7ad928510be800c4f004d9
	Issue introduced in 6.12 with commit e79e7c2df6277ee1ad9364a231f6183da4492415 and fixed in 7.0.11 with commit 0e2189ab095e3657f37b8295f3f2bbcde0f27529
	Issue introduced in 6.12 with commit e79e7c2df6277ee1ad9364a231f6183da4492415 and fixed in 7.1 with commit 5e121a81667a83e9a01d62b429e340f5a4a84abc

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-2026-64169
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/spi/spi-ep93xx.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/b6c0dabea07e25bd7db19a77ebfd0d02b9e2671a
	https://git.kernel.org/stable/c/8e027db9fa310b1d5e7ad928510be800c4f004d9
	https://git.kernel.org/stable/c/0e2189ab095e3657f37b8295f3f2bbcde0f27529
	https://git.kernel.org/stable/c/5e121a81667a83e9a01d62b429e340f5a4a84abc