---
id: CVE-2026-64121
title: 'net: ifb: report ethtool stats over num_tx_queues'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: ifb: report ethtool stats over num_tx_queues

  ifb_dev_init() allocates dp->tx_private to dev->num_tx_queues
  entries via kzalloc_objs(*txp, dev->num_tx_queues). Bot…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 <
    6afdb8113cb007f9332f59a9b7fd45731b8a9de5
  - >-
    Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 <
    16bd798cb6d8337d7c3eea1adc412f31b5181d5b
  - >-
    Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 <
    301a554e458e2f5ec47f2c336a7cb03b877f9fd6
  - >-
    Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 <
    f8a5a76b4a683043c6eff2a060bcaa17f9316ad5
  - >-
    Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 <
    2638e1773904d7aa8f24c6e7fda2ed7d69df6fa4
  - >-
    Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 <
    5db89c99566fc4728cc92e941d8e1975711e24b5
  - Linux 5.17
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:30:12.633352Z'
published: '2026-07-19'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:34:26.335Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-64121'
references:
  - url: 'https://git.kernel.org/stable/c/6afdb8113cb007f9332f59a9b7fd45731b8a9de5'
  - url: 'https://git.kernel.org/stable/c/16bd798cb6d8337d7c3eea1adc412f31b5181d5b'
  - url: 'https://git.kernel.org/stable/c/301a554e458e2f5ec47f2c336a7cb03b877f9fd6'
  - url: 'https://git.kernel.org/stable/c/f8a5a76b4a683043c6eff2a060bcaa17f9316ad5'
  - url: 'https://git.kernel.org/stable/c/2638e1773904d7aa8f24c6e7fda2ed7d69df6fa4'
  - url: 'https://git.kernel.org/stable/c/5db89c99566fc4728cc92e941d8e1975711e24b5'
tags:
  - cve.org
epss: 0.00126
epssPercentile: 0.02286
ingestedAt: '2026-11-06T16:57:43.234Z'
---

## Overview

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

net: ifb: report ethtool stats over num_tx_queues

ifb_dev_init() allocates dp->tx_private to dev->num_tx_queues
entries via kzalloc_objs(*txp, dev->num_tx_queues). Both IFB
per-queue RX and TX stats live in those entries: ifb_xmit() updates
txp->rx_stats using the skb queue mapping, ifb_ri_tasklet() updates
txp->tx_stats, and ifb_stats64() aggregates both over
dev->num_tx_queues.

The ethtool stats callbacks instead size and walk the per-queue
stats with dev->real_num_rx_queues and dev->real_num_tx_queues. With
an asymmetric device where the RX queue count exceeds the TX queue
count, for example:

    ip link add name ifb10 numtxqueues 1 numrxqueues 8 type ifb
    ethtool -S ifb10

ifb_get_ethtool_stats() indexes past the tx_private allocation and
copies adjacent slab data through ETHTOOL_GSTATS.

Use dev->num_tx_queues consistently for the stats strings, the
stats count, and the stats data walks. This reports one RX stats
group and one TX stats group for each backing ifb_q_private entry,
which is the queue set IFB can actually populate.

Reproduced under UML+KASAN at v7.1-rc2:

  BUG: KASAN: slab-out-of-bounds in ifb_fill_stats_data+0x3c/0xae
  Read of size 8 at addr 0000000062dbd228 by task ethtool/36
  ifb_fill_stats_data+0x3c/0xae
  ifb_get_ethtool_stats+0xc0/0x129
  __dev_ethtool+0x1ca5/0x363c
  dev_ethtool+0x123/0x1b3
  dev_ioctl+0x56c/0x744
  sock_do_ioctl+0x15f/0x1b2
  sock_ioctl+0x4d5/0x50a
  sys_ioctl+0xd8b/0xde9

With the patch applied, the same UML+KASAN repro is silent and
ethtool -S ifb10 reports only the stats backed by the single
allocated tx_private entry.

## Affected

- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 6afdb8113cb007f9332f59a9b7fd45731b8a9de5`
- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 16bd798cb6d8337d7c3eea1adc412f31b5181d5b`
- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 301a554e458e2f5ec47f2c336a7cb03b877f9fd6`
- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < f8a5a76b4a683043c6eff2a060bcaa17f9316ad5`
- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 2638e1773904d7aa8f24c6e7fda2ed7d69df6fa4`
- `Linux >= a21ee5b2fcb8d6d3973446c5039e966c4cfe40d1 < 5db89c99566fc4728cc92e941d8e1975711e24b5`
- `Linux 5.17`

## Remediation

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