From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-98655: perf: Require kernel access for text poke events
Date: Sun, 18 Oct 2026 17:43:50 +0200 [thread overview]
Message-ID: <2026101849-CVE-2026-98655-b30d@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
perf: Require kernel access for text poke events
Perf events with exclude_kernel=1 can be opened without kernel perf
access. However, exclude_kernel does not suppress text-poke sideband
records. Every PERF_RECORD_TEXT_POKE is marked PERF_RECORD_MISC_KERNEL
and contains a raw kernel instruction address.
An unprivileged task can therefore open and mmap a task-local software
event with text_poke=1. Both opening a count-only tracepoint event and
configuring UDP GRO for ESP-in-UDP cause updates to inline static calls;
the observer receives the relocated addresses of the modified instructions.
For a known kernel image, any such address reveals the runtime kernel
text base despite KASLR.
Call perf_allow_kernel() whenever attr.text_poke is set, regardless of
exclude_kernel. Events that neither monitor kernel execution nor request
text-poke records retain their existing permissions.
The Linux kernel CVE team has assigned CVE-2026-98655 to this issue.
Affected and fixed versions
===========================
Issue introduced in 5.9 with commit e17d43b93e544f5016c0251d2074c15568d5d963 and fixed in 6.12.113 with commit 8473f44db9f710ea6f8cafb22f2e3ba6cb8ca9a7
Issue introduced in 5.9 with commit e17d43b93e544f5016c0251d2074c15568d5d963 and fixed in 6.18.56 with commit e506333d1b9f42f1e402acebf1283af3c44a3809
Issue introduced in 5.9 with commit e17d43b93e544f5016c0251d2074c15568d5d963 and fixed in 7.2.10 with commit 677d0b51ac1a0db55d768c4c6399210b3de0795b
Issue introduced in 5.9 with commit e17d43b93e544f5016c0251d2074c15568d5d963 and fixed in 7.3-rc6 with commit 357e8a77a501d96c9517f01f4a211eed5e9c9184
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-2026-98655
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/events/core.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/8473f44db9f710ea6f8cafb22f2e3ba6cb8ca9a7
https://git.kernel.org/stable/c/e506333d1b9f42f1e402acebf1283af3c44a3809
https://git.kernel.org/stable/c/677d0b51ac1a0db55d768c4c6399210b3de0795b
https://git.kernel.org/stable/c/357e8a77a501d96c9517f01f4a211eed5e9c9184
reply other threads:[~2026-10-18 15:53 UTC|newest]
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