CVE-2026-23474: mtd: Avoid boot crash in RedBoot partition table parser

CVE-2026-23474: mtd: Avoid boot crash in RedBoot partition table parser

[Greg Kroah-Hartman]

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

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

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

mtd: Avoid boot crash in RedBoot partition table parser

Given CONFIG_FORTIFY_SOURCE=y and a recent compiler,
commit 439a1bcac648 ("fortify: Use __builtin_dynamic_object_size() when
available") produces the warning below and an oops.

    Searching for RedBoot partition table in 50000000.flash at offset 0x7e0000
    ------------[ cut here ]------------
    WARNING: lib/string_helpers.c:1035 at 0xc029e04c, CPU#0: swapper/0/1
    memcmp: detected buffer overflow: 15 byte read of buffer size 14
    Modules linked in:
    CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.19.0 #1 NONE

As Kees said, "'names' is pointing to the final 'namelen' many bytes
of the allocation ... 'namelen' could be basically any length at all.
This fortify warning looks legit to me -- this code used to be reading
beyond the end of the allocation."

Since the size of the dynamic allocation is calculated with strlen()
we can use strcmp() instead of memcmp() and remain within bounds.

The Linux kernel CVE team has assigned CVE-2026-23474 to this issue.


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

	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.1.167 with commit 0b08be5aca212a99f8ba786fee4922feac08002c
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.130 with commit d8570211a2b1ec886a462daa0be4e9983ac768bb
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.78 with commit 2025b2d1f9d5cad6ea6fe85654c6c41297c3130b
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.18.20 with commit c4054ad2d8bff4e8e937cd4a1d1a04c1e8f77a2c
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.19.10 with commit 75a4d8cfe7784f909b3bd69325abac8e04ecb385
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.0-rc5 with commit 8e2f8020270af7777d49c2e7132260983e4fc566

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-2026-23474
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/mtd/parsers/redboot.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/0b08be5aca212a99f8ba786fee4922feac08002c
	https://git.kernel.org/stable/c/d8570211a2b1ec886a462daa0be4e9983ac768bb
	https://git.kernel.org/stable/c/2025b2d1f9d5cad6ea6fe85654c6c41297c3130b
	https://git.kernel.org/stable/c/c4054ad2d8bff4e8e937cd4a1d1a04c1e8f77a2c
	https://git.kernel.org/stable/c/75a4d8cfe7784f909b3bd69325abac8e04ecb385
	https://git.kernel.org/stable/c/8e2f8020270af7777d49c2e7132260983e4fc566