cve/published/2025/CVE-2025-21891.mbox

From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: <linux-cve-announce@vger.kernel.org>
Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org>
Subject: CVE-2025-21891: ipvlan: ensure network headers are in skb linear part

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

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

ipvlan: ensure network headers are in skb linear part

syzbot found that ipvlan_process_v6_outbound() was assuming
the IPv6 network header isis present in skb->head [1]

Add the needed pskb_network_may_pull() calls for both
IPv4 and IPv6 handlers.

[1]
BUG: KMSAN: uninit-value in __ipv6_addr_type+0xa2/0x490 net/ipv6/addrconf_core.c:47
  __ipv6_addr_type+0xa2/0x490 net/ipv6/addrconf_core.c:47
  ipv6_addr_type include/net/ipv6.h:555 [inline]
  ip6_route_output_flags_noref net/ipv6/route.c:2616 [inline]
  ip6_route_output_flags+0x51/0x720 net/ipv6/route.c:2651
  ip6_route_output include/net/ip6_route.h:93 [inline]
  ipvlan_route_v6_outbound+0x24e/0x520 drivers/net/ipvlan/ipvlan_core.c:476
  ipvlan_process_v6_outbound drivers/net/ipvlan/ipvlan_core.c:491 [inline]
  ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:541 [inline]
  ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:605 [inline]
  ipvlan_queue_xmit+0xd72/0x1780 drivers/net/ipvlan/ipvlan_core.c:671
  ipvlan_start_xmit+0x5b/0x210 drivers/net/ipvlan/ipvlan_main.c:223
  __netdev_start_xmit include/linux/netdevice.h:5150 [inline]
  netdev_start_xmit include/linux/netdevice.h:5159 [inline]
  xmit_one net/core/dev.c:3735 [inline]
  dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3751
  sch_direct_xmit+0x399/0xd40 net/sched/sch_generic.c:343
  qdisc_restart net/sched/sch_generic.c:408 [inline]
  __qdisc_run+0x14da/0x35d0 net/sched/sch_generic.c:416
  qdisc_run+0x141/0x4d0 include/net/pkt_sched.h:127
  net_tx_action+0x78b/0x940 net/core/dev.c:5484
  handle_softirqs+0x1a0/0x7c0 kernel/softirq.c:561
  __do_softirq+0x14/0x1a kernel/softirq.c:595
  do_softirq+0x9a/0x100 kernel/softirq.c:462
  __local_bh_enable_ip+0x9f/0xb0 kernel/softirq.c:389
  local_bh_enable include/linux/bottom_half.h:33 [inline]
  rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline]
  __dev_queue_xmit+0x2758/0x57d0 net/core/dev.c:4611
  dev_queue_xmit include/linux/netdevice.h:3311 [inline]
  packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276
  packet_snd net/packet/af_packet.c:3132 [inline]
  packet_sendmsg+0x93e0/0xa7e0 net/packet/af_packet.c:3164
  sock_sendmsg_nosec net/socket.c:718 [inline]

The Linux kernel CVE team has assigned CVE-2025-21891 to this issue.


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

	Issue introduced in 3.19 with commit 2ad7bf3638411cb547f2823df08166c13ab04269 and fixed in 6.1.130 with commit 5b8dea8d1612dc7151d2457d7d2e6a69820309bf
	Issue introduced in 3.19 with commit 2ad7bf3638411cb547f2823df08166c13ab04269 and fixed in 6.6.81 with commit 4ec48f812804f370f622e0874e6dd8fcc58241cd
	Issue introduced in 3.19 with commit 2ad7bf3638411cb547f2823df08166c13ab04269 and fixed in 6.12.18 with commit 5353fd89663c48f56bdff975c562cfe78b1a2e4c
	Issue introduced in 3.19 with commit 2ad7bf3638411cb547f2823df08166c13ab04269 and fixed in 6.13.6 with commit e2a4f76a2d8a44816ecd25bcbdb47b786d621974
	Issue introduced in 3.19 with commit 2ad7bf3638411cb547f2823df08166c13ab04269 and fixed in 6.14 with commit 27843ce6ba3d3122b65066550fe33fb8839f8aef

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-2025-21891
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/ipvlan/ipvlan_core.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/5b8dea8d1612dc7151d2457d7d2e6a69820309bf
	https://git.kernel.org/stable/c/4ec48f812804f370f622e0874e6dd8fcc58241cd
	https://git.kernel.org/stable/c/5353fd89663c48f56bdff975c562cfe78b1a2e4c
	https://git.kernel.org/stable/c/e2a4f76a2d8a44816ecd25bcbdb47b786d621974
	https://git.kernel.org/stable/c/27843ce6ba3d3122b65066550fe33fb8839f8aef