From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-89742: rapidio: mport_cdev: fix use-after-free in dma_req_free()
Date: Fri, 11 Sep 2026 21:47:11 +0200 [thread overview]
Message-ID: <2026091105-CVE-2026-89742-450e@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
rapidio: mport_cdev: fix use-after-free in dma_req_free()
dma_req_free() acquires buf_mutex through req->map, drops the mapping
reference with kref_put(), and then dereferences req->map again to unlock
the mutex.
If kref_put() drops the last reference, mport_release_mapping() frees the
mapping, and the subsequent mutex_unlock() dereferences a freed object.
This is a use-after-free.
Fix this by caching map and md before kref_put(), clearing req->map while
holding buf_mutex, and using the cached md for mutex unlocking.
The bug is reachable from userspace via the RapidIO mport character device
interface.
The Linux kernel CVE team has assigned CVE-2026-89742 to this issue.
Affected and fixed versions
===========================
Issue introduced in 4.6 with commit e8de370188d098bb49483c287b44925957c3c9b6 and fixed in 6.12.109 with commit 9a9929ec875ff20922c90c96fd544ae8a2a61a8d
Issue introduced in 4.6 with commit e8de370188d098bb49483c287b44925957c3c9b6 and fixed in 6.18.50 with commit e6e925cc1f8067c65c7bec3da50a0ead3b3ef4e0
Issue introduced in 4.6 with commit e8de370188d098bb49483c287b44925957c3c9b6 and fixed in 7.2.4 with commit 211c68d817a3d9dc14c0026a59da7cac30f8147e
Issue introduced in 4.6 with commit e8de370188d098bb49483c287b44925957c3c9b6 and fixed in 7.3-rc1 with commit 5cbef379a94b161726c5f504598bf4791d45cedc
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-2026-89742
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:
drivers/rapidio/devices/rio_mport_cdev.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/9a9929ec875ff20922c90c96fd544ae8a2a61a8d
https://git.kernel.org/stable/c/e6e925cc1f8067c65c7bec3da50a0ead3b3ef4e0
https://git.kernel.org/stable/c/211c68d817a3d9dc14c0026a59da7cac30f8147e
https://git.kernel.org/stable/c/5cbef379a94b161726c5f504598bf4791d45cedc
reply other threads:[~2026-09-11 20:07 UTC|newest]
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