CVE-2026-81014: platform/x86: hp-bioscfg: fix heap OOB read in sk_store() and kek_store()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

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

platform/x86: hp-bioscfg: fix heap OOB read in sk_store() and kek_store()

sk_store() and kek_store() strip a trailing newline from the sysfs
write before allocating the key buffer:

	length = count;
	if (buf[length - 1] == '\n')
		length--;
	bioscfg_drv.spm_data.signing_key = kmemdup(buf, length, GFP_KERNEL);

but then pass the original "count" (not "length") as the copy size to
hp_wmi_perform_query(), which memcpy()s that many bytes out of the
"length"-sized allocation, reading one byte past it whenever the write
ends in a newline, the normal case for a shell "echo" into sysfs.

KASAN confirms this directly:

  BUG: KASAN: slab-out-of-bounds in hp_wmi_perform_query+0x1e9/0x460 [hp_bioscfg]
  Read of size 28 at addr ffff88813c8e2b80 by task python3/16022
  ...
  sk_store+0xa7/0x240 [hp_bioscfg]
  kernfs_fop_write_iter+0x3e1/0x5d0
  ...
  The buggy address is located 0 bytes inside of
  allocated 27-byte region [ffff88813c8e2b80, ffff88813c8e2b9b)

Reproduced identically for kek_store, and at multiple write sizes
(28, 57, 201 bytes), each time reading exactly one byte past a
kmemdup() allocation one byte smaller than the write.

Fix by passing "length" instead of "count" to hp_wmi_perform_query()
in both functions.

The Linux kernel CVE team has assigned CVE-2026-81014 to this issue.


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

	Issue introduced in 6.6 with commit b2715aa2e1352c0060b9dcba57a2e465bbfbcd68 and fixed in 6.12.109 with commit 4c6374dcb270d12907b880cf82a5a5ef21785fc3
	Issue introduced in 6.6 with commit b2715aa2e1352c0060b9dcba57a2e465bbfbcd68 and fixed in 6.18.50 with commit 7cd8fe01aba303a2382db0966eb6c8ab41d5f3c2
	Issue introduced in 6.6 with commit b2715aa2e1352c0060b9dcba57a2e465bbfbcd68 and fixed in 7.2.4 with commit 67b60703d7d8af1ca0e49f72e1bdb1ccecd41b5b
	Issue introduced in 6.6 with commit b2715aa2e1352c0060b9dcba57a2e465bbfbcd68 and fixed in 7.3-rc1 with commit a7508c7959ff8d037327d377ed21a9c0eabe4674

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-2026-81014
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/platform/x86/hp/hp-bioscfg/spmobj-attributes.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/4c6374dcb270d12907b880cf82a5a5ef21785fc3
	https://git.kernel.org/stable/c/7cd8fe01aba303a2382db0966eb6c8ab41d5f3c2
	https://git.kernel.org/stable/c/67b60703d7d8af1ca0e49f72e1bdb1ccecd41b5b
	https://git.kernel.org/stable/c/a7508c7959ff8d037327d377ed21a9c0eabe4674