CVE-2026-98528: gpio: cdev: fix kernel stack leak to user-space in error path

CVE-2026-98528: gpio: cdev: fix kernel stack leak to user-space in error path

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

gpio: cdev: fix kernel stack leak to user-space in error path

If we fail to acquire the GPIO chip guard in gpio_desc_to_lineinfo(), we
return immediately before zeroing the info struct we'll end up passing
to the user-space later in lineinfo_get_v1(). This may leak the kernel
stack contents. Make gpio_desc_to_lineinfo() return int so that the
-ENODEV returned on failure to acquire the guard can be propagated to
the callers.

While not strictly necessary: move the memset() before trying to acquire
the SRCU read lock too for good measure.

The Linux kernel CVE team has assigned CVE-2026-98528 to this issue.


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

	Issue introduced in 6.9 with commit d83cee3d2bb131c7fca7e19f1e33dc7530fd7083 and fixed in 6.12.112 with commit 8460ee5216ab9a38263b01dca4b0a27e083f70f3
	Issue introduced in 6.9 with commit d83cee3d2bb131c7fca7e19f1e33dc7530fd7083 and fixed in 6.18.55 with commit cf3d043582e106a0e57002bec8a6de8929ba3e1c
	Issue introduced in 6.9 with commit d83cee3d2bb131c7fca7e19f1e33dc7530fd7083 and fixed in 7.2.9 with commit 60a466f231905cd96ae6f0f3c44a710c97873dac
	Issue introduced in 6.9 with commit d83cee3d2bb131c7fca7e19f1e33dc7530fd7083 and fixed in 7.3-rc5 with commit 1feb5d39b05afd902ed9fc902ec5b15be03a4bdb

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-2026-98528
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/gpio/gpiolib-cdev.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/8460ee5216ab9a38263b01dca4b0a27e083f70f3
	https://git.kernel.org/stable/c/cf3d043582e106a0e57002bec8a6de8929ba3e1c
	https://git.kernel.org/stable/c/60a466f231905cd96ae6f0f3c44a710c97873dac
	https://git.kernel.org/stable/c/1feb5d39b05afd902ed9fc902ec5b15be03a4bdb