---
id: CVE-2026-43464
title: 'net/mlx5e: RX, Fix XDP multi-buf frag counting for legacy RQ'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/mlx5e: RX, Fix XDP multi-buf frag counting for legacy RQ

  XDP multi-buf programs can modify the layout of the XDP buffer when the
  program calls bpf_xdp_pull_data() …
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'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 72328f25755ee966724f46e3a0e8e59bef2091ba <
    1106412414dc3ee62999115be10ca83199b02108
  - >-
    Linux >= 0049fd63881505566824e88cfa624638f921c808 <
    9488ee96b4f53d2aed474c744f0ed64f61d1dcc9
  - >-
    Linux >= afd5ba577c10639f62e8120df67dc70ea4b61176 <
    c74557495efb4bd0adefdfc8678ecdbc82a06da3
  - >-
    Linux >= afd5ba577c10639f62e8120df67dc70ea4b61176 <
    03cb50e5b74fce8bf6d92b860371b66253cf0f8d
  - >-
    Linux >= afd5ba577c10639f62e8120df67dc70ea4b61176 <
    a6413e6f6c9d9bb9833324cb3753582f7bc0f2fa
  - Linux d969645b9b7810289bf3c353ea06957373756b8e
  - Linux >= 6.6.115 < 6.6.160
  - Linux >= 6.12.56 < 6.12.114
  - Linux >= 6.17.6 < 6.18
  - Linux 6.18
published: '2026-05-08'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T12:40:49.291Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43464'
references:
  - url: 'https://git.kernel.org/stable/c/1106412414dc3ee62999115be10ca83199b02108'
  - url: 'https://git.kernel.org/stable/c/9488ee96b4f53d2aed474c744f0ed64f61d1dcc9'
  - url: 'https://git.kernel.org/stable/c/c74557495efb4bd0adefdfc8678ecdbc82a06da3'
  - url: 'https://git.kernel.org/stable/c/03cb50e5b74fce8bf6d92b860371b66253cf0f8d'
  - url: 'https://git.kernel.org/stable/c/a6413e6f6c9d9bb9833324cb3753582f7bc0f2fa'
tags:
  - cve.org
epss: 0.00732
epssPercentile: 0.53772
ingestedAt: '2026-10-21T12:48:53.637Z'
---

## Overview

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

net/mlx5e: RX, Fix XDP multi-buf frag counting for legacy RQ

XDP multi-buf programs can modify the layout of the XDP buffer when the
program calls bpf_xdp_pull_data() or bpf_xdp_adjust_tail(). The
referenced commit in the fixes tag corrected the assumption in the mlx5
driver that the XDP buffer layout doesn't change during a program
execution. However, this fix introduced another issue: the dropped
fragments still need to be counted on the driver side to avoid page
fragment reference counting issues.

Such issue can be observed with the
test_xdp_native_adjst_tail_shrnk_data selftest when using a payload of
3600 and shrinking by 256 bytes (an upcoming selftest patch): the last
fragment gets released by the XDP code but doesn't get tracked by the
driver. This results in a negative pp_ref_count during page release and
the following splat:

  WARNING: include/net/page_pool/helpers.h:297 at mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core], CPU#12: ip/3137
  Modules linked in: [...]
  CPU: 12 UID: 0 PID: 3137 Comm: ip Not tainted 6.19.0-rc3+ #12 NONE
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
  RIP: 0010:mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core]
  [...]
  Call Trace:
   <TASK>
   mlx5e_dealloc_rx_wqe+0xcb/0x1a0 [mlx5_core]
   mlx5e_free_rx_descs+0x7f/0x110 [mlx5_core]
   mlx5e_close_rq+0x50/0x60 [mlx5_core]
   mlx5e_close_queues+0x36/0x2c0 [mlx5_core]
   mlx5e_close_channel+0x1c/0x50 [mlx5_core]
   mlx5e_close_channels+0x45/0x80 [mlx5_core]
   mlx5e_safe_switch_params+0x1a5/0x230 [mlx5_core]
   mlx5e_change_mtu+0xf3/0x2f0 [mlx5_core]
   netif_set_mtu_ext+0xf1/0x230
   do_setlink.isra.0+0x219/0x1180
   rtnl_newlink+0x79f/0xb60
   rtnetlink_rcv_msg+0x213/0x3a0
   netlink_rcv_skb+0x48/0xf0
   netlink_unicast+0x24a/0x350
   netlink_sendmsg+0x1ee/0x410
   __sock_sendmsg+0x38/0x60
   ____sys_sendmsg+0x232/0x280
   ___sys_sendmsg+0x78/0xb0
   __sys_sendmsg+0x5f/0xb0
   [...]
   do_syscall_64+0x57/0xc50

This patch fixes the issue by doing page frag counting on all the
original XDP buffer fragments for all relevant XDP actions (XDP_TX ,
XDP_REDIRECT and XDP_PASS). This is basically reverting to the original
counting before the commit in the fixes tag.

As frag_page is still pointing to the original tail, the nr_frags
parameter to xdp_update_skb_frags_info() needs to be calculated
in a different way to reflect the new nr_frags.

## Affected

- `Linux >= 72328f25755ee966724f46e3a0e8e59bef2091ba < 1106412414dc3ee62999115be10ca83199b02108`
- `Linux >= 0049fd63881505566824e88cfa624638f921c808 < 9488ee96b4f53d2aed474c744f0ed64f61d1dcc9`
- `Linux >= afd5ba577c10639f62e8120df67dc70ea4b61176 < c74557495efb4bd0adefdfc8678ecdbc82a06da3`
- `Linux >= afd5ba577c10639f62e8120df67dc70ea4b61176 < 03cb50e5b74fce8bf6d92b860371b66253cf0f8d`
- `Linux >= afd5ba577c10639f62e8120df67dc70ea4b61176 < a6413e6f6c9d9bb9833324cb3753582f7bc0f2fa`
- `Linux d969645b9b7810289bf3c353ea06957373756b8e`
- `Linux >= 6.6.115 < 6.6.160`
- `Linux >= 6.12.56 < 6.12.114`
- `Linux >= 6.17.6 < 6.18`
- `Linux 6.18`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.