From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89567: jbd2: bound shrinker scans by examined checkpoint buffers
Date: Fri, 11 Sep 2026 21:44:16 +0200 [thread overview]
Message-ID: <2026091125-CVE-2026-89567-dfb2@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
jbd2: bound shrinker scans by examined checkpoint buffers
The jbd2 shrinker currently accounts only checkpoint buffers that it
successfully releases against nr_to_scan. Busy buffers therefore do not
consume the scan budget.
If a checkpoint transaction contains mostly busy buffers, the shrinker
can scan its entire checkpoint list while holding journal->j_list_lock.
Large checkpoint lists can result in excessive lock hold times and leave
other CPUs spinning on j_list_lock, causing soft lockups or RCU stalls.
Pass nr_to_scan into journal_shrink_one_cp_list() and decrement it for
every buffer examined, including busy buffers. Pass NULL from checkpoint
cleanup paths so their existing full-list behavior is preserved.
This restores the scan-budget semantics that existed before
journal_shrink_one_cp_list() was changed to always scan a complete
checkpoint list.
The Linux kernel CVE team has assigned CVE-2026-89567 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.5 with commit b98dba273a0e47dbfade89c9af73c5b012a4eabb and fixed in 6.12.109 with commit edf5fcd0469b7467bd5b37a79502c8d9c3257dbb
Issue introduced in 6.5 with commit b98dba273a0e47dbfade89c9af73c5b012a4eabb and fixed in 6.18.50 with commit 71c6b872c746465fa4b5def239cb296173ca8216
Issue introduced in 6.5 with commit b98dba273a0e47dbfade89c9af73c5b012a4eabb and fixed in 7.2.4 with commit c2c0fb364685b8996c357d3b050394959b29d6e0
Issue introduced in 6.5 with commit b98dba273a0e47dbfade89c9af73c5b012a4eabb and fixed in 7.3-rc1 with commit 15cb16496446b94e67f7abcb049b8e2c75cd3d02
Issue introduced in 5.15.129 with commit 9c31bb2684f8035beca0275349d19d679b679ffb
Issue introduced in 6.1.50 with commit 5fda50e262e65bd553ff777c4b280afd1495a18b
Issue introduced in 6.4.13 with commit 557fda9ed70ebf8eda2620ba3d746215285a1303
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-2026-89567
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:
fs/jbd2/checkpoint.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/edf5fcd0469b7467bd5b37a79502c8d9c3257dbb
https://git.kernel.org/stable/c/71c6b872c746465fa4b5def239cb296173ca8216
https://git.kernel.org/stable/c/c2c0fb364685b8996c357d3b050394959b29d6e0
https://git.kernel.org/stable/c/15cb16496446b94e67f7abcb049b8e2c75cd3d02
reply other threads:[~2026-09-11 19:56 UTC|newest]
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