From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-43285: mm/slab: do not access current->mems_allowed_seq if !allow_spin
Date: Fri, 8 May 2026 15:11:50 +0200 [thread overview]
Message-ID: <2026050850-CVE-2026-43285-4680@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
mm/slab: do not access current->mems_allowed_seq if !allow_spin
Lockdep complains when get_from_any_partial() is called in an NMI
context, because current->mems_allowed_seq is seqcount_spinlock_t and
not NMI-safe:
================================
WARNING: inconsistent lock state
6.19.0-rc5-kfree-rcu+ #315 Tainted: G N
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
kunit_try_catch/9989 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff889085799820 (&____s->seqcount#3){.-.-}-{0:0}, at: ___slab_alloc+0x58f/0xc00
{INITIAL USE} state was registered at:
lock_acquire+0x185/0x320
kernel_init_freeable+0x391/0x1150
kernel_init+0x1f/0x220
ret_from_fork+0x736/0x8f0
ret_from_fork_asm+0x1a/0x30
irq event stamp: 56
hardirqs last enabled at (55): [<ffffffff850a68d7>] _raw_spin_unlock_irq+0x27/0x70
hardirqs last disabled at (56): [<ffffffff850858ca>] __schedule+0x2a8a/0x6630
softirqs last enabled at (0): [<ffffffff81536711>] copy_process+0x1dc1/0x6a10
softirqs last disabled at (0): [<0000000000000000>] 0x0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&____s->seqcount#3);
<Interrupt>
lock(&____s->seqcount#3);
*** DEADLOCK ***
According to Documentation/locking/seqlock.rst, seqcount_t is not
NMI-safe and seqcount_latch_t should be used when read path can interrupt
the write-side critical section. In this case, do not access
current->mems_allowed_seq and avoid retry.
The Linux kernel CVE team has assigned CVE-2026-43285 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.18 with commit af92793e52c3a99b828ed4bdd277fd3e11c18d08 and fixed in 6.18.16 with commit 353dd9934447b9193643ae1afd938607a74d4915
Issue introduced in 6.18 with commit af92793e52c3a99b828ed4bdd277fd3e11c18d08 and fixed in 6.19.6 with commit efd767ddcef0669bbd33c6a823ea0a88f06d4b29
Issue introduced in 6.18 with commit af92793e52c3a99b828ed4bdd277fd3e11c18d08 and fixed in 7.0 with commit 144080a5823b2dbd635acb6decf7ab23182664f3
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-2026-43285
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:
mm/slub.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/353dd9934447b9193643ae1afd938607a74d4915
https://git.kernel.org/stable/c/efd767ddcef0669bbd33c6a823ea0a88f06d4b29
https://git.kernel.org/stable/c/144080a5823b2dbd635acb6decf7ab23182664f3
reply other threads:[~2026-05-08 13:15 UTC|newest]
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