linux-cve-announce - CVE-2025-68800: mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats

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Message-ID: <2026011307-CVE-2025-68800-39d2@gregkh>
Date: Tue, 13 Jan 2026 16:29:26 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68800: mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats

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

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

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

mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats

Cited commit added a dedicated mutex (instead of RTNL) to protect the
multicast route list, so that it will not change while the driver
periodically traverses it in order to update the kernel about multicast
route stats that were queried from the device.

One instance of list entry deletion (during route replace) was missed
and it can result in a use-after-free [1].

Fix by acquiring the mutex before deleting the entry from the list and
releasing it afterwards.

[1]
BUG: KASAN: slab-use-after-free in mlxsw_sp_mr_stats_update+0x4a5/0x540 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:1006 [mlxsw_spectrum]
Read of size 8 at addr ffff8881523c2fa8 by task kworker/2:5/22043

CPU: 2 UID: 0 PID: 22043 Comm: kworker/2:5 Not tainted 6.18.0-rc1-custom-g1a3d6d7cd014 #1 PREEMPT(full)
Hardware name: Mellanox Technologies Ltd. MSN2010/SA002610, BIOS 5.6.5 08/24/2017
Workqueue: mlxsw_core mlxsw_sp_mr_stats_update [mlxsw_spectrum]
Call Trace:
 <TASK>
 dump_stack_lvl+0xba/0x110
 print_report+0x174/0x4f5
 kasan_report+0xdf/0x110
 mlxsw_sp_mr_stats_update+0x4a5/0x540 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:1006 [mlxsw_spectrum]
 process_one_work+0x9cc/0x18e0
 worker_thread+0x5df/0xe40
 kthread+0x3b8/0x730
 ret_from_fork+0x3e9/0x560
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 29933:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 __kasan_kmalloc+0x8f/0xa0
 mlxsw_sp_mr_route_add+0xd8/0x4770 [mlxsw_spectrum]
 mlxsw_sp_router_fibmr_event_work+0x371/0xad0 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:7965 [mlxsw_spectrum]
 process_one_work+0x9cc/0x18e0
 worker_thread+0x5df/0xe40
 kthread+0x3b8/0x730
 ret_from_fork+0x3e9/0x560
 ret_from_fork_asm+0x1a/0x30

Freed by task 29933:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 __kasan_save_free_info+0x3b/0x70
 __kasan_slab_free+0x43/0x70
 kfree+0x14e/0x700
 mlxsw_sp_mr_route_add+0x2dea/0x4770 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:444 [mlxsw_spectrum]
 mlxsw_sp_router_fibmr_event_work+0x371/0xad0 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:7965 [mlxsw_spectrum]
 process_one_work+0x9cc/0x18e0
 worker_thread+0x5df/0xe40
 kthread+0x3b8/0x730
 ret_from_fork+0x3e9/0x560
 ret_from_fork_asm+0x1a/0x30

The Linux kernel CVE team has assigned CVE-2025-68800 to this issue.


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

	Issue introduced in 5.7 with commit f38656d067257cc43b652958dd154e1ab0773701 and fixed in 6.1.160 with commit 37ca08b35a27ce8fd8e74dd3fd2ae21c23b63b73
	Issue introduced in 5.7 with commit f38656d067257cc43b652958dd154e1ab0773701 and fixed in 6.6.120 with commit 5f2831fc593c2b2efbff7dd0dd7441cec76adcd5
	Issue introduced in 5.7 with commit f38656d067257cc43b652958dd154e1ab0773701 and fixed in 6.12.64 with commit 216afc198484fde110ebeafc017992266f4596ce
	Issue introduced in 5.7 with commit f38656d067257cc43b652958dd154e1ab0773701 and fixed in 6.18.3 with commit 4049a6ace209f4ed150429f86ae796d7d6a4c22b
	Issue introduced in 5.7 with commit f38656d067257cc43b652958dd154e1ab0773701 and fixed in 6.19-rc2 with commit 8ac1dacec458f55f871f7153242ed6ab60373b90

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-2025-68800
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/net/ethernet/mellanox/mlxsw/spectrum_mr.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/37ca08b35a27ce8fd8e74dd3fd2ae21c23b63b73
	https://git.kernel.org/stable/c/5f2831fc593c2b2efbff7dd0dd7441cec76adcd5
	https://git.kernel.org/stable/c/216afc198484fde110ebeafc017992266f4596ce
	https://git.kernel.org/stable/c/4049a6ace209f4ed150429f86ae796d7d6a4c22b
	https://git.kernel.org/stable/c/8ac1dacec458f55f871f7153242ed6ab60373b90