CVE-2026-98798

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

State: Published
Severity: Not scored
Published: Oct 18, 2026
Updated: Oct 30, 2026
Reserved: Sep 25, 2026

Description

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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	9f4ca05827a27ec73bf63a42732f1978b8a779af to before 51e76b4113e5147329ed8dd232375bf11fd34044Affected 9f4ca05827a27ec73bf63a42732f1978b8a779af to before 213ff02ab26a4543ef02b4db393bbdd5fa5679a7Affected 9f4ca05827a27ec73bf63a42732f1978b8a779af to before 0d867b91598b6ed2f75998c34f4e2869631da31eAffected 9f4ca05827a27ec73bf63a42732f1978b8a779af to before 2294b62eaec6fd3c76a261d287f66641eeafd5f0Affected 9f4ca05827a27ec73bf63a42732f1978b8a779af to before d870102b5425390cab42eebbf3d19ec6a43c6734Affected 9f4ca05827a27ec73bf63a42732f1978b8a779af to before 19419faf58dfe5bcc8a9e60e622976c5f8e3ddc1Affected
LinuxLinux	4.17Affected before 4.17Not affected 6.1.191 through 6.1.Not affected 6.6.160 through 6.6.Not affected 6.12.113 through 6.12.Not affected 6.18.56 through 6.18.Not affected 7.2.10 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

9f4ca05827a27ec73bf63a42732f1978b8a779af to before 51e76b4113e5147329ed8dd232375bf11fd34044Affected
9f4ca05827a27ec73bf63a42732f1978b8a779af to before 213ff02ab26a4543ef02b4db393bbdd5fa5679a7Affected
9f4ca05827a27ec73bf63a42732f1978b8a779af to before 0d867b91598b6ed2f75998c34f4e2869631da31eAffected
9f4ca05827a27ec73bf63a42732f1978b8a779af to before 2294b62eaec6fd3c76a261d287f66641eeafd5f0Affected
9f4ca05827a27ec73bf63a42732f1978b8a779af to before d870102b5425390cab42eebbf3d19ec6a43c6734Affected
9f4ca05827a27ec73bf63a42732f1978b8a779af to before 19419faf58dfe5bcc8a9e60e622976c5f8e3ddc1Affected

LinuxLinux

4.17Affected
before 4.17Not affected
6.1.191 through 6.1.*Not affected
6.6.160 through 6.6.*Not affected
6.12.113 through 6.12.*Not affected
6.18.56 through 6.18.*Not affected
7.2.10 through 7.2.*Not affected
7.3 and laterNot affected

References

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