CVE-2021-46905: net: hso: fix NULL-deref on disconnect regression

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-02-26 · updated 2026-06-17
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: net: hso: fix NULL-deref on disconnect regression Commit 8a12f8836145 ("net: hso: fix null-ptr-deref during tty device unregistration") fixed the racy minor allocation reported by syzbot, but introduced an unconditional NULL-pointer dereference on every disconnect instead. Specifically, the serial device table must no longer be accessed after the minor has been released by hso_serial_tty_unregister().

Affected products

Linux kernel: before 4.19.189; from 4.20.0 before 5.4.115; from 5.5.0 before 5.10.33; from 5.11.0 before 5.11.17; 5.12, 5.12-rc1, 5.12-rc2, 5.12-rc3, 5.12-rc4, 5.12-rc5 (+2) — fixed in 4.19.189, 5.10.33, 5.11.17, 5.4.115

How to fix

Upgrade to a fixed version: Linux kernel 4.19.189, 5.10.33, 5.11.17, 5.4.115. Check the vendor advisory for mitigations.

References

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