---
id: CVE-2025-21925
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  llc: do not use skb_get() before dev_queue_xmit()

  syzbot is able to crash hosts [1], using llc and devices
  not supporting IFF_TX_SKB_SHARING.

  In this case, e1000 driv…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  llc: do not use skb_get() before dev_queue_xmit()

  syzbot is able to crash hosts [1], using llc and devices
  not supporting IFF_TX_SKB_SHARING.

  In this case, e1000 driv…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 2.6.13, < 5.4.291'
  - 'linux_kernel >= 5.5, < 5.10.235'
  - 'linux_kernel >= 5.11, < 5.15.179'
  - 'linux_kernel >= 5.16, < 6.1.131'
  - 'linux_kernel >= 6.2, < 6.6.83'
  - 'linux_kernel >= 6.7, < 6.12.19'
  - 'linux_kernel >= 6.13, < 6.13.7'
  - linux_kernel = 2.6.12
  - linux_kernel = 6.14
patched:
  - linux_kernel 6.13.7
published: '2025-04-01'
updated: '2026-07-14'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-21925'
references:
  - url: 'https://git.kernel.org/stable/c/056e8a46d79e22983bae4267e0d9c52927076f46'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/0f764208dc24ea043c3e20194d32aebf94f8459c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/13f3f872627f0f27c31245524fc11367756240ad'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/17f86e25431ebc15aa9245ff156414fdad47822d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/416e8b4c20c6398044e93008deefd563289f477d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/64e6a754d33d31aa844b3ee66fb93ac84ca1565e'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9b6f083db141ece0024be01526aa05aa978811cb'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/cd1c44327bbbd50fc24f2b38892f5f328b784d0f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00222
epssPercentile: 0.11573
ingestedAt: '2026-07-14T13:36:56.071Z'
---

## Overview

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

llc: do not use skb_get() before dev_queue_xmit()

syzbot is able to crash hosts [1], using llc and devices
not supporting IFF_TX_SKB_SHARING.

In this case, e1000 driver calls eth_skb_pad(), while
the skb is shared.

Simply replace skb_get() by skb_clone() in net/llc/llc_s_ac.c

Note that e1000 driver might have an issue with pktgen,
because it does not clear IFF_TX_SKB_SHARING, this is an
orthogonal change.

We need to audit other skb_get() uses in net/llc.

[1]

kernel BUG at net/core/skbuff.c:2178 !
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 16371 Comm: syz.2.2764 Not tainted 6.14.0-rc4-syzkaller-00052-gac9c34d1e45a #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
 RIP: 0010:pskb_expand_head+0x6ce/0x1240 net/core/skbuff.c:2178
Call Trace:
 <TASK>
  __skb_pad+0x18a/0x610 net/core/skbuff.c:2466
  __skb_put_padto include/linux/skbuff.h:3843 [inline]
  skb_put_padto include/linux/skbuff.h:3862 [inline]
  eth_skb_pad include/linux/etherdevice.h:656 [inline]
  e1000_xmit_frame+0x2d99/0x5800 drivers/net/ethernet/intel/e1000/e1000_main.c:3128
  __netdev_start_xmit include/linux/netdevice.h:5151 [inline]
  netdev_start_xmit include/linux/netdevice.h:5160 [inline]
  xmit_one net/core/dev.c:3806 [inline]
  dev_hard_start_xmit+0x9a/0x7b0 net/core/dev.c:3822
  sch_direct_xmit+0x1ae/0xc30 net/sched/sch_generic.c:343
  __dev_xmit_skb net/core/dev.c:4045 [inline]
  __dev_queue_xmit+0x13d4/0x43e0 net/core/dev.c:4621
  dev_queue_xmit include/linux/netdevice.h:3313 [inline]
  llc_sap_action_send_test_c+0x268/0x320 net/llc/llc_s_ac.c:144
  llc_exec_sap_trans_actions net/llc/llc_sap.c:153 [inline]
  llc_sap_next_state net/llc/llc_sap.c:182 [inline]
  llc_sap_state_process+0x239/0x510 net/llc/llc_sap.c:209
  llc_ui_sendmsg+0xd0d/0x14e0 net/llc/af_llc.c:993
  sock_sendmsg_nosec net/socket.c:718 [inline]

## Affected

- `linux_kernel >= 2.6.13, < 5.4.291`
- `linux_kernel >= 5.5, < 5.10.235`
- `linux_kernel >= 5.11, < 5.15.179`
- `linux_kernel >= 5.16, < 6.1.131`
- `linux_kernel >= 6.2, < 6.6.83`
- `linux_kernel >= 6.7, < 6.12.19`
- `linux_kernel >= 6.13, < 6.13.7`
- `linux_kernel = 2.6.12`
- `linux_kernel = 6.14`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.13.7`