linux-cve-announce - CVE-2026-23211: mm, swap: restore swap

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Message-ID: <2026021830-CVE-2026-23211-10d0@gregkh>
Date: Wed, 18 Feb 2026 15:16:31 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23211: mm, swap: restore swap_space attr aviod kernel panic

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

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

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

mm, swap: restore swap_space attr aviod kernel panic

commit 8b47299a411a ("mm, swap: mark swap address space ro and add context
debug check") made the swap address space read-only.  It may lead to
kernel panic if arch_prepare_to_swap returns a failure under heavy memory
pressure as follows,

el1_abort+0x40/0x64
el1h_64_sync_handler+0x48/0xcc
el1h_64_sync+0x84/0x88
errseq_set+0x4c/0xb8 (P)
__filemap_set_wb_err+0x20/0xd0
shrink_folio_list+0xc20/0x11cc
evict_folios+0x1520/0x1be4
try_to_shrink_lruvec+0x27c/0x3dc
shrink_one+0x9c/0x228
shrink_node+0xb3c/0xeac
do_try_to_free_pages+0x170/0x4f0
try_to_free_pages+0x334/0x534
__alloc_pages_direct_reclaim+0x90/0x158
__alloc_pages_slowpath+0x334/0x588
__alloc_frozen_pages_noprof+0x224/0x2fc
__folio_alloc_noprof+0x14/0x64
vma_alloc_zeroed_movable_folio+0x34/0x44
do_pte_missing+0xad4/0x1040
handle_mm_fault+0x4a4/0x790
do_page_fault+0x288/0x5f8
do_translation_fault+0x38/0x54
do_mem_abort+0x54/0xa8

Restore swap address space as not ro to avoid the panic.

The Linux kernel CVE team has assigned CVE-2026-23211 to this issue.


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

	Issue introduced in 6.18 with commit 8b47299a411a178d572aaac31ff7ab33a8bd27e2 and fixed in 6.18.9 with commit b0020cbd26380177b9fb8b7e75a8f7bdba79db20
	Issue introduced in 6.18 with commit 8b47299a411a178d572aaac31ff7ab33a8bd27e2 and fixed in 6.19 with commit a0f3c0845a4ff68d403c568266d17e9cc553e561

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-2026-23211
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/swap.h
	mm/swap_state.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/b0020cbd26380177b9fb8b7e75a8f7bdba79db20
	https://git.kernel.org/stable/c/a0f3c0845a4ff68d403c568266d17e9cc553e561