linux-cve-announce - CVE-2025-37880: um: work around sched_yield not yielding in time-travel mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025050943-CVE-2025-37880-3f3c@gregkh>
Date: Fri,  9 May 2025 08:45:47 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-37880: um: work around sched_yield not yielding in time-travel mode

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

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

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

um: work around sched_yield not yielding in time-travel mode

sched_yield by a userspace may not actually cause scheduling in
time-travel mode as no time has passed. In the case seen it appears to
be a badly implemented userspace spinlock in ASAN. Unfortunately, with
time-travel it causes an extreme slowdown or even deadlock depending on
the kernel configuration (CONFIG_UML_MAX_USERSPACE_ITERATIONS).

Work around it by accounting time to the process whenever it executes a
sched_yield syscall.

The Linux kernel CVE team has assigned CVE-2025-37880 to this issue.


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

	Fixed in 6.12.26 with commit da780c4a075ba2deb05ae29f0af4a990578c7901
	Fixed in 6.14.5 with commit 990ddc65173776f1e01e7135d8c1fd5f8fd4d5d2
	Fixed in 6.15-rc1 with commit 887c5c12e80c8424bd471122d2e8b6b462e12874

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-2025-37880
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:
	arch/um/include/linux/time-internal.h
	arch/um/kernel/skas/syscall.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/da780c4a075ba2deb05ae29f0af4a990578c7901
	https://git.kernel.org/stable/c/990ddc65173776f1e01e7135d8c1fd5f8fd4d5d2
	https://git.kernel.org/stable/c/887c5c12e80c8424bd471122d2e8b6b462e12874