CVE-2026-53294: mailbox: mailbox-test: don't free the reused channel

CVE-2026-53294: mailbox: mailbox-test: don't free the reused channel

[Greg Kroah-Hartman]

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

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

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

mailbox: mailbox-test: don't free the reused channel

The RX channel can be aliased to the TX channel if it has a different
MMIO. This special case needs to be handled when freeing the channels
otherwise a double-free occurs.

The Linux kernel CVE team has assigned CVE-2026-53294 to this issue.


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

	Issue introduced in 4.4 with commit 8ea4484d0c2bb4e2152261943fa1a3522654b1c7 and fixed in 5.10.258 with commit fc0089f82c3e36060c2c79156bc2018bfb16b56b
	Issue introduced in 4.4 with commit 8ea4484d0c2bb4e2152261943fa1a3522654b1c7 and fixed in 5.15.209 with commit 5d4f3d0f64f1016cb78b400a70b67df91fac99b5
	Issue introduced in 4.4 with commit 8ea4484d0c2bb4e2152261943fa1a3522654b1c7 and fixed in 6.1.175 with commit c494a11da45ad7ec9b0ff216c3e3ace351193bb6
	Issue introduced in 4.4 with commit 8ea4484d0c2bb4e2152261943fa1a3522654b1c7 and fixed in 6.6.141 with commit 3afca89fae501dbd7421e1777b5b8f033b1d98d0
	Issue introduced in 4.4 with commit 8ea4484d0c2bb4e2152261943fa1a3522654b1c7 and fixed in 6.12.91 with commit 5c209299b0113e289e238fa5f2e8f00c59f76060
	Issue introduced in 4.4 with commit 8ea4484d0c2bb4e2152261943fa1a3522654b1c7 and fixed in 6.18.33 with commit 82f6dcea46cf5de65c4ba7283f7c7b34de4a324d
	Issue introduced in 4.4 with commit 8ea4484d0c2bb4e2152261943fa1a3522654b1c7 and fixed in 7.0.10 with commit 240c71a2aea36a1a4210f911a1c32ea88777e8e4
	Issue introduced in 4.4 with commit 8ea4484d0c2bb4e2152261943fa1a3522654b1c7 and fixed in 7.1 with commit 88ebadbf0deefdaccdab868b44ff70a0a257f473

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-2026-53294
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/mailbox/mailbox-test.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/fc0089f82c3e36060c2c79156bc2018bfb16b56b
	https://git.kernel.org/stable/c/5d4f3d0f64f1016cb78b400a70b67df91fac99b5
	https://git.kernel.org/stable/c/c494a11da45ad7ec9b0ff216c3e3ace351193bb6
	https://git.kernel.org/stable/c/3afca89fae501dbd7421e1777b5b8f033b1d98d0
	https://git.kernel.org/stable/c/5c209299b0113e289e238fa5f2e8f00c59f76060
	https://git.kernel.org/stable/c/82f6dcea46cf5de65c4ba7283f7c7b34de4a324d
	https://git.kernel.org/stable/c/240c71a2aea36a1a4210f911a1c32ea88777e8e4
	https://git.kernel.org/stable/c/88ebadbf0deefdaccdab868b44ff70a0a257f473