linux-cve-announce - CVE-2022-50817: net: hsr: avoid possible NULL deref in skb

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Message-ID: <2025123015-CVE-2022-50817-55d8@gregkh>
Date: Tue, 30 Dec 2025 13:09:21 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50817: net: hsr: avoid possible NULL deref in skb_clone()

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

net: hsr: avoid possible NULL deref in skb_clone()

syzbot got a crash [1] in skb_clone(), caused by a bug
in hsr_get_untagged_frame().

When/if create_stripped_skb_hsr() returns NULL, we must
not attempt to call skb_clone().

While we are at it, replace a WARN_ONCE() by netdev_warn_once().

[1]
general protection fault, probably for non-canonical address 0xdffffc000000000f: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000078-0x000000000000007f]
CPU: 1 PID: 754 Comm: syz-executor.0 Not tainted 6.0.0-syzkaller-02734-g0326074ff465 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
RIP: 0010:skb_clone+0x108/0x3c0 net/core/skbuff.c:1641
Code: 93 02 00 00 49 83 7c 24 28 00 0f 85 e9 00 00 00 e8 5d 4a 29 fa 4c 8d 75 7e 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <0f> b6 04 02 4c 89 f2 83 e2 07 38 d0 7f 08 84 c0 0f 85 9e 01 00 00
RSP: 0018:ffffc90003ccf4e0 EFLAGS: 00010207

RAX: dffffc0000000000 RBX: ffffc90003ccf5f8 RCX: ffffc9000c24b000
RDX: 000000000000000f RSI: ffffffff8751cb13 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00000000000000f0 R09: 0000000000000140
R10: fffffbfff181d972 R11: 0000000000000000 R12: ffff888161fc3640
R13: 0000000000000a20 R14: 000000000000007e R15: ffffffff8dc5f620
FS: 00007feb621e4700(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feb621e3ff8 CR3: 00000001643a9000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
hsr_get_untagged_frame+0x4e/0x610 net/hsr/hsr_forward.c:164
hsr_forward_do net/hsr/hsr_forward.c:461 [inline]
hsr_forward_skb+0xcca/0x1d50 net/hsr/hsr_forward.c:623
hsr_handle_frame+0x588/0x7c0 net/hsr/hsr_slave.c:69
__netif_receive_skb_core+0x9fe/0x38f0 net/core/dev.c:5379
__netif_receive_skb_one_core+0xae/0x180 net/core/dev.c:5483
__netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5599
netif_receive_skb_internal net/core/dev.c:5685 [inline]
netif_receive_skb+0x12f/0x8d0 net/core/dev.c:5744
tun_rx_batched+0x4ab/0x7a0 drivers/net/tun.c:1544
tun_get_user+0x2686/0x3a00 drivers/net/tun.c:1995
tun_chr_write_iter+0xdb/0x200 drivers/net/tun.c:2025
call_write_iter include/linux/fs.h:2187 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x9e9/0xdd0 fs/read_write.c:584
ksys_write+0x127/0x250 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The Linux kernel CVE team has assigned CVE-2022-50817 to this issue.


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

	Issue introduced in 3.17 with commit f266a683a4804dc499efc6c2206ef68efed029d0 and fixed in 5.10.152 with commit ff7ba766758313129794f150bbc4d351b5e17a53
	Issue introduced in 3.17 with commit f266a683a4804dc499efc6c2206ef68efed029d0 and fixed in 5.15.76 with commit 35ece858660eae13ee0242496a1956c39d29418e
	Issue introduced in 3.17 with commit f266a683a4804dc499efc6c2206ef68efed029d0 and fixed in 6.0.6 with commit c46f2e0fcd1ecfc6046e5cf785ff89f0572f94e4
	Issue introduced in 3.17 with commit f266a683a4804dc499efc6c2206ef68efed029d0 and fixed in 6.1 with commit d8b57135fd9ffe9a5b445350a686442a531c5339

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-2022-50817
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/hsr/hsr_forward.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/ff7ba766758313129794f150bbc4d351b5e17a53
	https://git.kernel.org/stable/c/35ece858660eae13ee0242496a1956c39d29418e
	https://git.kernel.org/stable/c/c46f2e0fcd1ecfc6046e5cf785ff89f0572f94e4
	https://git.kernel.org/stable/c/d8b57135fd9ffe9a5b445350a686442a531c5339