CVE-2026-80584: s390/qeth: validate user buffer length in SNMP and ARP query ioctls

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

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

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

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

s390/qeth: validate user buffer length in SNMP and ARP query ioctls

qeth_snmp_command() and qeth_l3_arp_query() allocate a buffer sized by
a user-supplied length (udata_len) without checking a lower bound, then
set udata_offset to a fixed non-zero value and pass both to a reply
callback. The callback bounds-checks the copy with

        if ((udata_len - udata_offset) < len)

Both fields are u32, so a udata_len smaller than udata_offset makes the
subtraction wrap and the check pass, and the following memcpy() writes
past the allocation. A udata_len of 0 also yields ZERO_SIZE_PTR from
kzalloc(), which the existing NULL check does not catch.

Reject buffers smaller than udata_offset before allocating, so the
callback subtraction can no longer underflow.

The Linux kernel CVE team has assigned CVE-2026-80584 to this issue.


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

	Issue introduced in 2.6.26 with commit 4a71df50047f0db65ea09b1be155852e81a45eba and fixed in 5.10.266 with commit 9d00eeb2d27f4cc817c5e408760226d43f811ec6
	Issue introduced in 2.6.26 with commit 4a71df50047f0db65ea09b1be155852e81a45eba and fixed in 5.15.217 with commit 46443eaddebd84c51940857b11787229be169dec
	Issue introduced in 2.6.26 with commit 4a71df50047f0db65ea09b1be155852e81a45eba and fixed in 6.1.184 with commit 91935843f9396a9e45253e2c0d4337ca1371754b
	Issue introduced in 2.6.26 with commit 4a71df50047f0db65ea09b1be155852e81a45eba and fixed in 6.6.153 with commit cc423f4105fe145b33e1d7cad34245a798358f73
	Issue introduced in 2.6.26 with commit 4a71df50047f0db65ea09b1be155852e81a45eba and fixed in 6.12.105 with commit 3083818e67bcd656965797fbac9a3d6c1d44f78a
	Issue introduced in 2.6.26 with commit 4a71df50047f0db65ea09b1be155852e81a45eba and fixed in 6.18.46 with commit a3083647747942ea32faf14560d6397ff3068046
	Issue introduced in 2.6.26 with commit 4a71df50047f0db65ea09b1be155852e81a45eba and fixed in 7.1.10 with commit 75fb3151513d7d9f77a8f9545418279b119c06b8
	Issue introduced in 2.6.26 with commit 4a71df50047f0db65ea09b1be155852e81a45eba and fixed in 7.2 with commit d141f087b1af656f055d7c5793a3e87817ba0bbe

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-2026-80584
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/s390/net/qeth_core_main.c
	drivers/s390/net/qeth_l3_main.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/9d00eeb2d27f4cc817c5e408760226d43f811ec6
	https://git.kernel.org/stable/c/46443eaddebd84c51940857b11787229be169dec
	https://git.kernel.org/stable/c/91935843f9396a9e45253e2c0d4337ca1371754b
	https://git.kernel.org/stable/c/cc423f4105fe145b33e1d7cad34245a798358f73
	https://git.kernel.org/stable/c/3083818e67bcd656965797fbac9a3d6c1d44f78a
	https://git.kernel.org/stable/c/a3083647747942ea32faf14560d6397ff3068046
	https://git.kernel.org/stable/c/75fb3151513d7d9f77a8f9545418279b119c06b8
	https://git.kernel.org/stable/c/d141f087b1af656f055d7c5793a3e87817ba0bbe