Subject: CVE-2024-26665: tunnels: fix out of bounds access when building IPv6 PMTU error

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

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

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

tunnels: fix out of bounds access when building IPv6 PMTU error

If the ICMPv6 error is built from a non-linear skb we get the following
splat,

  BUG: KASAN: slab-out-of-bounds in do_csum+0x220/0x240
  Read of size 4 at addr ffff88811d402c80 by task netperf/820
  CPU: 0 PID: 820 Comm: netperf Not tainted 6.8.0-rc1+ #543
  ...
   kasan_report+0xd8/0x110
   do_csum+0x220/0x240
   csum_partial+0xc/0x20
   skb_tunnel_check_pmtu+0xeb9/0x3280
   vxlan_xmit_one+0x14c2/0x4080
   vxlan_xmit+0xf61/0x5c00
   dev_hard_start_xmit+0xfb/0x510
   __dev_queue_xmit+0x7cd/0x32a0
   br_dev_queue_push_xmit+0x39d/0x6a0

Use skb_checksum instead of csum_partial who cannot deal with non-linear
SKBs.

The Linux kernel CVE team has assigned CVE-2024-26665 to this issue.

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

	Issue introduced in 5.9 with commit 4cb47a8644cc and fixed in 5.10.210 with commit e77bf828f1ca
	Issue introduced in 5.9 with commit 4cb47a8644cc and fixed in 5.15.149 with commit d964dd1bc145
	Issue introduced in 5.9 with commit 4cb47a8644cc and fixed in 6.1.78 with commit e37cde7a5716
	Issue introduced in 5.9 with commit 4cb47a8644cc and fixed in 6.6.17 with commit 510c869ffa40
	Issue introduced in 5.9 with commit 4cb47a8644cc and fixed in 6.7.5 with commit 7dc9feb8b170
	Issue introduced in 5.9 with commit 4cb47a8644cc and fixed in 6.8 with commit d75abeec401f

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-2024-26665
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/ipv4/ip_tunnel_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/e77bf828f1ca1c47fcff58bdc26b60a9d3dfbe1d
	https://git.kernel.org/stable/c/d964dd1bc1452594b4207d9229c157d9386e5d8a
	https://git.kernel.org/stable/c/e37cde7a5716466ff2a76f7f27f0a29b05b9a732
	https://git.kernel.org/stable/c/510c869ffa4068c5f19ff4df51d1e2f3a30aaac1
	https://git.kernel.org/stable/c/7dc9feb8b1705cf00de20563b6bc4831f4c99dab
	https://git.kernel.org/stable/c/d75abeec401f8c86b470e7028a13fcdc87e5dd06