---
id: CVE-2026-98798
title: 'net: bcmgenet: fix NULL dereference in set_coalesce before first open'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: bcmgenet: fix NULL dereference in set_coalesce before first open

  The Rx ring priv and index are only set in bcmgenet_init_rx_ring(),
  which runs at open. Setting t…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 9f4ca05827a27ec73bf63a42732f1978b8a779af <
    0d867b91598b6ed2f75998c34f4e2869631da31e
  - >-
    Linux >= 9f4ca05827a27ec73bf63a42732f1978b8a779af <
    2294b62eaec6fd3c76a261d287f66641eeafd5f0
  - >-
    Linux >= 9f4ca05827a27ec73bf63a42732f1978b8a779af <
    d870102b5425390cab42eebbf3d19ec6a43c6734
  - >-
    Linux >= 9f4ca05827a27ec73bf63a42732f1978b8a779af <
    19419faf58dfe5bcc8a9e60e622976c5f8e3ddc1
  - Linux 4.17
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:48:43.367Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98798'
references:
  - url: 'https://git.kernel.org/stable/c/0d867b91598b6ed2f75998c34f4e2869631da31e'
  - url: 'https://git.kernel.org/stable/c/2294b62eaec6fd3c76a261d287f66641eeafd5f0'
  - url: 'https://git.kernel.org/stable/c/d870102b5425390cab42eebbf3d19ec6a43c6734'
  - url: 'https://git.kernel.org/stable/c/19419faf58dfe5bcc8a9e60e622976c5f8e3ddc1'
tags:
  - cve.org
ingestedAt: '2026-10-18T16:47:32.483Z'
---

## Overview

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

net: bcmgenet: fix NULL dereference in set_coalesce before first open

The Rx ring priv and index are only set in bcmgenet_init_rx_ring(),
which runs at open. Setting the Rx coalescing parameters on an interface
that was never opened, e.g. "ethtool -C eth0 rx-usecs 50", dereferences
a NULL ring->priv. The oops happens with RTNL held, so networking
stays stuck until a reboot:

  Unable to handle kernel paging request at virtual address 0000000000002788
  pc : bcmgenet_set_rx_coalesce.isra.0+0x10/0x88
  lr : bcmgenet_set_coalesce+0xe8/0x180
  Call trace:
   bcmgenet_set_rx_coalesce.isra.0+0x10/0x88 (P)
   __ethnl_set_coalesce.isra.0+0x490/0x570
   ethnl_set_coalesce+0x48/0xc0
   ethnl_default_set_doit+0xf4/0x230
   genl_family_rcv_msg_doit+0xe8/0x160
   genl_rcv_msg+0x220/0x2a0
   netlink_rcv_skb+0x68/0x140
   genl_rcv+0x40/0x60
   netlink_unicast+0x338/0x3c0
   netlink_sendmsg+0x19c/0x3f8
   __sock_sendmsg+0x64/0xc0
   __sys_sendto+0x124/0x198
   __arm64_sys_sendto+0x30/0x48

Set priv and index at probe. Writing the registers while the interface
is down is harmless because open resets the MAC and
bcmgenet_init_rx_coalesce() reapplies the stored values.

It was observed on a Raspberry Pi CM4, but should apply to all other
genet devices.

## Affected

- `Linux >= 9f4ca05827a27ec73bf63a42732f1978b8a779af < 0d867b91598b6ed2f75998c34f4e2869631da31e`
- `Linux >= 9f4ca05827a27ec73bf63a42732f1978b8a779af < 2294b62eaec6fd3c76a261d287f66641eeafd5f0`
- `Linux >= 9f4ca05827a27ec73bf63a42732f1978b8a779af < d870102b5425390cab42eebbf3d19ec6a43c6734`
- `Linux >= 9f4ca05827a27ec73bf63a42732f1978b8a779af < 19419faf58dfe5bcc8a9e60e622976c5f8e3ddc1`
- `Linux 4.17`

## Remediation

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