Subject: CVE-2023-52574: team: fix null-ptr-deref when team device type is changed

From: Greg Kroah-Hartman <[email-masked]>

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

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

team: fix null-ptr-deref when team device type is changed

Get a null-ptr-deref bug as follows with reproducer [1].

BUG: kernel NULL pointer dereference, address: 0000000000000228
...
RIP: 0010:vlan_dev_hard_header+0x35/0x140 [8021q]
...
Call Trace:
 <TASK>
 ? __die+0x24/0x70
 ? page_fault_oops+0x82/0x150
 ? exc_page_fault+0x69/0x150
 ? asm_exc_page_fault+0x26/0x30
 ? vlan_dev_hard_header+0x35/0x140 [8021q]
 ? vlan_dev_hard_header+0x8e/0x140 [8021q]
 neigh_connected_output+0xb2/0x100
 ip6_finish_output2+0x1cb/0x520
 ? nf_hook_slow+0x43/0xc0
 ? ip6_mtu+0x46/0x80
 ip6_finish_output+0x2a/0xb0
 mld_sendpack+0x18f/0x250
 mld_ifc_work+0x39/0x160
 process_one_work+0x1e6/0x3f0
 worker_thread+0x4d/0x2f0
 ? __pfx_worker_thread+0x10/0x10
 kthread+0xe5/0x120
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x34/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1b/0x30

[1]
$ teamd -t team0 -d -c '{"runner": {"name": "loadbalance"}}'
$ ip link add name t-dummy type dummy
$ ip link add link t-dummy name t-dummy.100 type vlan id 100
$ ip link add name t-nlmon type nlmon
$ ip link set t-nlmon master team0
$ ip link set t-nlmon nomaster
$ ip link set t-dummy up
$ ip link set team0 up
$ ip link set t-dummy.100 down
$ ip link set t-dummy.100 master team0

When enslave a vlan device to team device and team device type is changed
from non-ether to ether, header_ops of team device is changed to
vlan_header_ops. That is incorrect and will trigger null-ptr-deref
for vlan->real_dev in vlan_dev_hard_header() because team device is not
a vlan device.

Cache eth_header_ops in team_setup(), then assign cached header_ops to
header_ops of team net device when its type is changed from non-ether
to ether to fix the bug.

The Linux kernel CVE team has assigned CVE-2023-52574 to this issue.

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

	Issue introduced in 3.7 with commit 1d76efe1577b and fixed in 4.14.327 with commit 1779eb51b9cc
	Issue introduced in 3.7 with commit 1d76efe1577b and fixed in 4.19.296 with commit a7fb47b97111
	Issue introduced in 3.7 with commit 1d76efe1577b and fixed in 5.4.258 with commit c5f6478686bb
	Issue introduced in 3.7 with commit 1d76efe1577b and fixed in 5.10.198 with commit b44dd92e2afd
	Issue introduced in 3.7 with commit 1d76efe1577b and fixed in 5.15.134 with commit cd05eec2ee0c
	Issue introduced in 3.7 with commit 1d76efe1577b and fixed in 6.1.56 with commit 2f0acb0736ec
	Issue introduced in 3.7 with commit 1d76efe1577b and fixed in 6.5.6 with commit cac50d9f5d87
	Issue introduced in 3.7 with commit 1d76efe1577b and fixed in 6.6 with commit 492032760127

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-2023-52574
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/team/team.c
	include/linux/if_team.h

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/1779eb51b9cc628cee551f252701a85a2a50a457
	https://git.kernel.org/stable/c/a7fb47b9711101d2405b0eb1276fb1f9b9b270c7
	https://git.kernel.org/stable/c/c5f6478686bb45f453031594ae19b6c9723a780d
	https://git.kernel.org/stable/c/b44dd92e2afd89eb6e9d27616858e72a67bdc1a7
	https://git.kernel.org/stable/c/cd05eec2ee0cc396813a32ef675634e403748255
	https://git.kernel.org/stable/c/2f0acb0736ecc3eb85dc80ad2790d634dcb10b58
	https://git.kernel.org/stable/c/cac50d9f5d876be32cb9aa21c74018468900284d
	https://git.kernel.org/stable/c/492032760127251e5540a5716a70996bacf2a3fd