Subject: CVE-2024-42321: net: flow_dissector: use DEBUG_NET_WARN_ON_ONCE

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

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

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

net: flow_dissector: use DEBUG_NET_WARN_ON_ONCE

The following splat is easy to reproduce upstream as well as in -stable
kernels. Florian Westphal provided the following commit:

  d1dab4f71d37 ("net: add and use __skb_get_hash_symmetric_net")

but this complementary fix has been also suggested by Willem de Bruijn
and it can be easily backported to -stable kernel which consists in
using DEBUG_NET_WARN_ON_ONCE instead to silence the following splat
given __skb_get_hash() is used by the nftables tracing infrastructure to
to identify packets in traces.

[69133.561393] ------------[ cut here ]------------
[69133.561404] WARNING: CPU: 0 PID: 43576 at net/core/flow_dissector.c:1104 __skb_flow_dissect+0x134f/
[...]
[69133.561944] CPU: 0 PID: 43576 Comm: socat Not tainted 6.10.0-rc7+ #379
[69133.561959] RIP: 0010:__skb_flow_dissect+0x134f/0x2ad0
[69133.561970] Code: 83 f9 04 0f 84 b3 00 00 00 45 85 c9 0f 84 aa 00 00 00 41 83 f9 02 0f 84 81 fc ff
ff 44 0f b7 b4 24 80 00 00 00 e9 8b f9 ff ff <0f> 0b e9 20 f3 ff ff 41 f6 c6 20 0f 84 e4 ef ff ff 48 8d 7b 12 e8
[69133.561979] RSP: 0018:ffffc90000006fc0 EFLAGS: 00010246
[69133.561988] RAX: 0000000000000000 RBX: ffffffff82f33e20 RCX: ffffffff81ab7e19
[69133.561994] RDX: dffffc0000000000 RSI: ffffc90000007388 RDI: ffff888103a1b418
[69133.562001] RBP: ffffc90000007310 R08: 0000000000000000 R09: 0000000000000000
[69133.562007] R10: ffffc90000007388 R11: ffffffff810cface R12: ffff888103a1b400
[69133.562013] R13: 0000000000000000 R14: ffffffff82f33e2a R15: ffffffff82f33e28
[69133.562020] FS:  00007f40f7131740(0000) GS:ffff888390800000(0000) knlGS:0000000000000000
[69133.562027] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[69133.562033] CR2: 00007f40f7346ee0 CR3: 000000015d200001 CR4: 00000000001706f0
[69133.562040] Call Trace:
[69133.562044]  <IRQ>
[69133.562049]  ? __warn+0x9f/0x1a0
[ 1211.841384]  ? __skb_flow_dissect+0x107e/0x2860
[...]
[ 1211.841496]  ? bpf_flow_dissect+0x160/0x160
[ 1211.841753]  __skb_get_hash+0x97/0x280
[ 1211.841765]  ? __skb_get_hash_symmetric+0x230/0x230
[ 1211.841776]  ? mod_find+0xbf/0xe0
[ 1211.841786]  ? get_stack_info_noinstr+0x12/0xe0
[ 1211.841798]  ? bpf_ksym_find+0x56/0xe0
[ 1211.841807]  ? __rcu_read_unlock+0x2a/0x70
[ 1211.841819]  nft_trace_init+0x1b9/0x1c0 [nf_tables]
[ 1211.841895]  ? nft_trace_notify+0x830/0x830 [nf_tables]
[ 1211.841964]  ? get_stack_info+0x2b/0x80
[ 1211.841975]  ? nft_do_chain_arp+0x80/0x80 [nf_tables]
[ 1211.842044]  nft_do_chain+0x79c/0x850 [nf_tables]

The Linux kernel CVE team has assigned CVE-2024-42321 to this issue.

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

	Issue introduced in 5.2 with commit 9b52e3f267a6 and fixed in 6.1.103 with commit eb03d9826aa6
	Issue introduced in 5.2 with commit 9b52e3f267a6 and fixed in 6.6.44 with commit 4afbac11f2f6
	Issue introduced in 5.2 with commit 9b52e3f267a6 and fixed in 6.10.3 with commit c5d21aabf1b3
	Issue introduced in 5.2 with commit 9b52e3f267a6 and fixed in 6.11 with commit 120f1c857a73

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-2024-42321
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/core/flow_dissector.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/eb03d9826aa646577342a952d658d4598381c035
	https://git.kernel.org/stable/c/4afbac11f2f629d1e62817c4e210bdfaa7521107
	https://git.kernel.org/stable/c/c5d21aabf1b31a79f228508af33aee83456bc1b0
	https://git.kernel.org/stable/c/120f1c857a73e52132e473dee89b340440cb692b