cve/published/2022/CVE-2022-49812.mbox

From bippy-1.1.0 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@kernel.org>
To: <linux-cve-announce@vger.kernel.org>
Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
Subject: CVE-2022-49812: bridge: switchdev: Fix memory leaks when changing VLAN protocol

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

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

bridge: switchdev: Fix memory leaks when changing VLAN protocol

The bridge driver can offload VLANs to the underlying hardware either
via switchdev or the 8021q driver. When the former is used, the VLAN is
marked in the bridge driver with the 'BR_VLFLAG_ADDED_BY_SWITCHDEV'
private flag.

To avoid the memory leaks mentioned in the cited commit, the bridge
driver will try to delete a VLAN via the 8021q driver if the VLAN is not
marked with the previously mentioned flag.

When the VLAN protocol of the bridge changes, switchdev drivers are
notified via the 'SWITCHDEV_ATTR_ID_BRIDGE_VLAN_PROTOCOL' attribute, but
the 8021q driver is also called to add the existing VLANs with the new
protocol and delete them with the old protocol.

In case the VLANs were offloaded via switchdev, the above behavior is
both redundant and buggy. Redundant because the VLANs are already
programmed in hardware and drivers that support VLAN protocol change
(currently only mlx5) change the protocol upon the switchdev attribute
notification. Buggy because the 8021q driver is called despite these
VLANs being marked with 'BR_VLFLAG_ADDED_BY_SWITCHDEV'. This leads to
memory leaks [1] when the VLANs are deleted.

Fix by not calling the 8021q driver for VLANs that were already
programmed via switchdev.

[1]
unreferenced object 0xffff8881f6771200 (size 256):
  comm "ip", pid 446855, jiffies 4298238841 (age 55.240s)
  hex dump (first 32 bytes):
    00 00 7f 0e 83 88 ff ff 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000012819ac>] vlan_vid_add+0x437/0x750
    [<00000000f2281fad>] __br_vlan_set_proto+0x289/0x920
    [<000000000632b56f>] br_changelink+0x3d6/0x13f0
    [<0000000089d25f04>] __rtnl_newlink+0x8ae/0x14c0
    [<00000000f6276baf>] rtnl_newlink+0x5f/0x90
    [<00000000746dc902>] rtnetlink_rcv_msg+0x336/0xa00
    [<000000001c2241c0>] netlink_rcv_skb+0x11d/0x340
    [<0000000010588814>] netlink_unicast+0x438/0x710
    [<00000000e1a4cd5c>] netlink_sendmsg+0x788/0xc40
    [<00000000e8992d4e>] sock_sendmsg+0xb0/0xe0
    [<00000000621b8f91>] ____sys_sendmsg+0x4ff/0x6d0
    [<000000000ea26996>] ___sys_sendmsg+0x12e/0x1b0
    [<00000000684f7e25>] __sys_sendmsg+0xab/0x130
    [<000000004538b104>] do_syscall_64+0x3d/0x90
    [<0000000091ed9678>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

The Linux kernel CVE team has assigned CVE-2022-49812 to this issue.


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

	Issue introduced in 5.0 with commit 279737939a8194f02fa352ab4476a1b241f44ef4 and fixed in 5.10.157 with commit 347f1793b573466424c550f2748ed837b6690fe7
	Issue introduced in 5.0 with commit 279737939a8194f02fa352ab4476a1b241f44ef4 and fixed in 5.15.80 with commit fc16a2c81a3eb1cbba8775f5bdc67856df903a7c
	Issue introduced in 5.0 with commit 279737939a8194f02fa352ab4476a1b241f44ef4 and fixed in 6.0.10 with commit f8926e2d2225eb7b7e11cd3fa266aaad9075b767
	Issue introduced in 5.0 with commit 279737939a8194f02fa352ab4476a1b241f44ef4 and fixed in 6.1 with commit 9d45921ee4cb364910097e7d1b7558559c2f9fd2

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-2022-49812
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:
	net/bridge/br_vlan.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/347f1793b573466424c550f2748ed837b6690fe7
	https://git.kernel.org/stable/c/fc16a2c81a3eb1cbba8775f5bdc67856df903a7c
	https://git.kernel.org/stable/c/f8926e2d2225eb7b7e11cd3fa266aaad9075b767
	https://git.kernel.org/stable/c/9d45921ee4cb364910097e7d1b7558559c2f9fd2