---
id: CVE-2022-49142
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: preserve skb_end_offset() in skb_unclone_keeptruesize()

  syzbot found another way to trigger the infamous WARN_ON_ONCE(delta < len)
  in skb_try_coalesce() [1]

  I wa…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: preserve skb_end_offset() in skb_unclone_keeptruesize()

  syzbot found another way to trigger the infamous WARN_ON_ONCE(delta < len)
  in skb_try_coalesce() [1]

  I wa…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 4.4.260, < 4.5'
  - 'linux_kernel >= 4.9.260, < 4.10'
  - 'linux_kernel >= 4.14.224, < 4.15'
  - 'linux_kernel >= 4.19.179, < 4.20'
  - 'linux_kernel >= 5.4.103, < 5.5'
  - 'linux_kernel >= 5.10.21, < 5.11'
  - 'linux_kernel >= 5.11.4, < 5.15.33'
  - 'linux_kernel >= 5.16, < 5.16.19'
  - 'linux_kernel >= 5.17, < 5.17.2'
patched:
  - linux_kernel 5.17.2
published: '2025-02-26'
updated: '2026-10-03'
sourceUpdated: '2026-10-03T11:17:26.413'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2022-49142'
references:
  - url: 'https://git.kernel.org/stable/c/23629b673b780d967b88a850b1518cf0f0ffc6aa'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2b88cba55883eaafbc9b7cbff0b2c7cdba71ed01'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/91c118727432a5d776d5fe86e0cf8eb1289ac1fc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a903e516f5df44b46d526b403d93e7be1a425538'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a9a6d30264327d8ff7f23da33e7a77ffb793fa3f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
epss: 0.00644
epssPercentile: 0.49036
ingestedAt: '2026-10-03T11:43:42.105Z'
---

## Overview

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

net: preserve skb_end_offset() in skb_unclone_keeptruesize()

syzbot found another way to trigger the infamous WARN_ON_ONCE(delta < len)
in skb_try_coalesce() [1]

I was able to root cause the issue to kfence.

When kfence is in action, the following assertion is no longer true:

int size = xxxx;
void *ptr1 = kmalloc(size, gfp);
void *ptr2 = kmalloc(size, gfp);

if (ptr1 && ptr2)
	ASSERT(ksize(ptr1) == ksize(ptr2));

We attempted to fix these issues in the blamed commits, but forgot
that TCP was possibly shifting data after skb_unclone_keeptruesize()
has been used, notably from tcp_retrans_try_collapse().

So we not only need to keep same skb->truesize value,
we also need to make sure TCP wont fill new tailroom
that pskb_expand_head() was able to get from a
addr = kmalloc(...) followed by ksize(addr)

Split skb_unclone_keeptruesize() into two parts:

1) Inline skb_unclone_keeptruesize() for the common case,
   when skb is not cloned.

2) Out of line __skb_unclone_keeptruesize() for the 'slow path'.

WARNING: CPU: 1 PID: 6490 at net/core/skbuff.c:5295 skb_try_coalesce+0x1235/0x1560 net/core/skbuff.c:5295
Modules linked in:
CPU: 1 PID: 6490 Comm: syz-executor161 Not tainted 5.17.0-rc4-syzkaller-00229-g4f12b742eb2b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:skb_try_coalesce+0x1235/0x1560 net/core/skbuff.c:5295
Code: bf 01 00 00 00 0f b7 c0 89 c6 89 44 24 20 e8 62 24 4e fa 8b 44 24 20 83 e8 01 0f 85 e5 f0 ff ff e9 87 f4 ff ff e8 cb 20 4e fa <0f> 0b e9 06 f9 ff ff e8 af b2 95 fa e9 69 f0 ff ff e8 95 b2 95 fa
RSP: 0018:ffffc900063af268 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 00000000ffffffd5 RCX: 0000000000000000
RDX: ffff88806fc05700 RSI: ffffffff872abd55 RDI: 0000000000000003
RBP: ffff88806e675500 R08: 00000000ffffffd5 R09: 0000000000000000
R10: ffffffff872ab659 R11: 0000000000000000 R12: ffff88806dd554e8
R13: ffff88806dd9bac0 R14: ffff88806dd9a2c0 R15: 0000000000000155
FS:  00007f18014f9700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020002000 CR3: 000000006be7a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tcp_try_coalesce net/ipv4/tcp_input.c:4651 [inline]
 tcp_try_coalesce+0x393/0x920 net/ipv4/tcp_input.c:4630
 tcp_queue_rcv+0x8a/0x6e0 net/ipv4/tcp_input.c:4914
 tcp_data_queue+0x11fd/0x4bb0 net/ipv4/tcp_input.c:5025
 tcp_rcv_established+0x81e/0x1ff0 net/ipv4/tcp_input.c:5947
 tcp_v4_do_rcv+0x65e/0x980 net/ipv4/tcp_ipv4.c:1719
 sk_backlog_rcv include/net/sock.h:1037 [inline]
 __release_sock+0x134/0x3b0 net/core/sock.c:2779
 release_sock+0x54/0x1b0 net/core/sock.c:3311
 sk_wait_data+0x177/0x450 net/core/sock.c:2821
 tcp_recvmsg_locked+0xe28/0x1fd0 net/ipv4/tcp.c:2457
 tcp_recvmsg+0x137/0x610 net/ipv4/tcp.c:2572
 inet_recvmsg+0x11b/0x5e0 net/ipv4/af_inet.c:850
 sock_recvmsg_nosec net/socket.c:948 [inline]
 sock_recvmsg net/socket.c:966 [inline]
 sock_recvmsg net/socket.c:962 [inline]
 ____sys_recvmsg+0x2c4/0x600 net/socket.c:2632
 ___sys_recvmsg+0x127/0x200 net/socket.c:2674
 __sys_recvmsg+0xe2/0x1a0 net/socket.c:2704
 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+0x44/0xae

## Affected

- `linux_kernel >= 4.4.260, < 4.5`
- `linux_kernel >= 4.9.260, < 4.10`
- `linux_kernel >= 4.14.224, < 4.15`
- `linux_kernel >= 4.19.179, < 4.20`
- `linux_kernel >= 5.4.103, < 5.5`
- `linux_kernel >= 5.10.21, < 5.11`
- `linux_kernel >= 5.11.4, < 5.15.33`
- `linux_kernel >= 5.16, < 5.16.19`
- `linux_kernel >= 5.17, < 5.17.2`

## Remediation

Upgrade past the affected range:

- `linux_kernel 5.17.2`