linux-cve-announce - CVE-2025-21993: iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show

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Message-ID: <2025040257-CVE-2025-21993-54d1@gregkh>
Date: Wed,  2 Apr 2025 13:52:00 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21993: iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()

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

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

iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()

When performing an iSCSI boot using IPv6, iscsistart still reads the
/sys/firmware/ibft/ethernetX/subnet-mask entry. Since the IPv6 prefix
length is 64, this causes the shift exponent to become negative,
triggering a UBSAN warning. As the concept of a subnet mask does not
apply to IPv6, the value is set to ~0 to suppress the warning message.

The Linux kernel CVE team has assigned CVE-2025-21993 to this issue.


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

	Fixed in 6.1.132 with commit 9bfa80c8aa4e06dff55a953c3fffbfc68a3a3b1c
	Fixed in 6.6.84 with commit 2d1eef248107bdf3d5a69d0fde04c30a79a7bf5d
	Fixed in 6.12.20 with commit b253660fac5e0e9080d2c95e3a029e1898d49afb
	Fixed in 6.13.8 with commit c1c6e527470e5eab0b2d57bd073530fbace39eab
	Fixed in 6.14 with commit 07e0d99a2f701123ad3104c0f1a1e66bce74d6e5

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-2025-21993
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/firmware/iscsi_ibft.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/9bfa80c8aa4e06dff55a953c3fffbfc68a3a3b1c
	https://git.kernel.org/stable/c/2d1eef248107bdf3d5a69d0fde04c30a79a7bf5d
	https://git.kernel.org/stable/c/b253660fac5e0e9080d2c95e3a029e1898d49afb
	https://git.kernel.org/stable/c/c1c6e527470e5eab0b2d57bd073530fbace39eab
	https://git.kernel.org/stable/c/07e0d99a2f701123ad3104c0f1a1e66bce74d6e5