From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89748: tracing: Fix retry exhaustion in simple ring buffer reader swap
Date: Fri, 11 Sep 2026 21:47:17 +0200 [thread overview]
Message-ID: <2026091106-CVE-2026-89748-ec03@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix retry exhaustion in simple ring buffer reader swap
simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
post-decrements it only after a failed link replacement. On the final
attempt, a successful replacement leaves retry at zero, while a failed
replacement leaves it at -1.
The current !retry test reverses both outcomes. It returns an error after
a successful final replacement, leaving the link update complete but the
reader bookkeeping unfinished. After a failed final replacement, it
falls through and updates the head and reader pointers as though the
replacement succeeded, which can corrupt the ring.
Treat only a negative counter as exhaustion and return the documented
-EBUSY error.
The Linux kernel CVE team has assigned CVE-2026-89748 to this issue.
Affected and fixed versions
===========================
Issue introduced in 7.1 with commit 34e5b958bdad0f9cf16306368bbc2dc5b2a50143 and fixed in 7.2.4 with commit df02489aa3aa1834659f0d20c89f7d212047d268
Issue introduced in 7.1 with commit 34e5b958bdad0f9cf16306368bbc2dc5b2a50143 and fixed in 7.3-rc1 with commit e0d3aed7b12cf37b74c7cc5265073d0263b49cde
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-2026-89748
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:
kernel/trace/simple_ring_buffer.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/df02489aa3aa1834659f0d20c89f7d212047d268
https://git.kernel.org/stable/c/e0d3aed7b12cf37b74c7cc5265073d0263b49cde
reply other threads:[~2026-09-11 20:05 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2026091106-CVE-2026-89748-ec03@gregkh \
--to=gregkh@linuxfoundation.org \
--cc=cve@kernel.org \
--cc=gregkh@kernel.org \
--cc=linux-cve-announce@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox