CVE-2026-89988: kprobes: Protect kprobe_blacklist with RCU

CVE-2026-89988: kprobes: Protect kprobe_blacklist with RCU

[Greg Kroah-Hartman]

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

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

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

kprobes: Protect kprobe_blacklist with RCU

__within_kprobe_blacklist() traverses kprobe_blacklist without holding
kprobe_mutex. When a module is unloaded, kprobe_remove_area_blacklist()
removes blacklist entries and immediately frees them with kfree().
A concurrent call to within_kprobe_blacklist() can therefore dereference
freed memory.

Furthermore, within_kprobe_blacklist() can be called in atomic or
non-preemptible contexts where the sleeping kprobe_mutex cannot be taken.

Protect kprobe_blacklist with RCU. Use guard(rcu)() and
list_for_each_entry_rcu() for traversal, list_add_tail_rcu() for
insertions, list_del_rcu() for deletions, and kfree_rcu() to reclaim
entries safely after a grace period.

The Linux kernel CVE team has assigned CVE-2026-89988 to this issue.


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

	Issue introduced in 3.16 with commit 376e242429bf8539ef39a080ac113c8799840b13 and fixed in 6.1.188 with commit 8f406205003f741225f620f0e357ca0de71d45e3
	Issue introduced in 3.16 with commit 376e242429bf8539ef39a080ac113c8799840b13 and fixed in 6.6.157 with commit 630ed8734a02b992e8a97538179c2ece42c5210f
	Issue introduced in 3.16 with commit 376e242429bf8539ef39a080ac113c8799840b13 and fixed in 6.12.110 with commit 518d9b5568bb06f86e4434f7a30faa9612ea91ad
	Issue introduced in 3.16 with commit 376e242429bf8539ef39a080ac113c8799840b13 and fixed in 6.18.51 with commit 5da247e4d1e8661d4d6f997101d59967e8994e32
	Issue introduced in 3.16 with commit 376e242429bf8539ef39a080ac113c8799840b13 and fixed in 7.2.5 with commit 6e62cf983a2bd547e6bbd3f935539233e5f97f8f
	Issue introduced in 3.16 with commit 376e242429bf8539ef39a080ac113c8799840b13 and fixed in 7.3-rc2 with commit 0c4256196b3a105307e2235fbfd85e768bbcdd0f

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-2026-89988
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:
	include/linux/kprobes.h
	kernel/kprobes.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/8f406205003f741225f620f0e357ca0de71d45e3
	https://git.kernel.org/stable/c/630ed8734a02b992e8a97538179c2ece42c5210f
	https://git.kernel.org/stable/c/518d9b5568bb06f86e4434f7a30faa9612ea91ad
	https://git.kernel.org/stable/c/5da247e4d1e8661d4d6f997101d59967e8994e32
	https://git.kernel.org/stable/c/6e62cf983a2bd547e6bbd3f935539233e5f97f8f
	https://git.kernel.org/stable/c/0c4256196b3a105307e2235fbfd85e768bbcdd0f