What’s Vulnerable › Vulnerabilities

CVE-2024-40966: tty: add the option to have a tty reject a new ldisc

• 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: 2024-07-12 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: tty: add the option to have a tty reject a new ldisc ... and use it to limit the virtual terminals to just N_TTY. They are kind of special, and in particular, the "con_write()" routine violates the "writes cannot sleep" rule that some ldiscs rely on. This avoids the BUG: sleeping function called from invalid context at kernel/printk/printk.c:2659 when N_GSM has been attached to a virtual console, and gsmld_write() calls con_write() while holding a spinlock, and con_write() then tries to get the console lock.

Affected products

• Linux kernel: before 6.1.96; from 6.2 before 6.6.36; from 6.7 before 6.9.7 — fixed in 6.1.96, 6.6.36, 6.9.7

How to fix

Upgrade to a fixed version: Linux kernel 6.1.96, 6.6.36, 6.9.7. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/287b569a5b914903ba7c438a3c0dbc3410ebb409
• https://git.kernel.org/stable/c/3c6332f3bb1578b5b10ac2561247b1d6272ae937
• https://git.kernel.org/stable/c/5920ac19964f9e20181f63b410d9200ddbf8dc86
• https://git.kernel.org/stable/c/6bd23e0c2bb6c65d4f5754d1456bc9a4427fc59b
• https://git.kernel.org/stable/c/287b569a5b914903ba7c438a3c0dbc3410ebb409
• https://git.kernel.org/stable/c/3c6332f3bb1578b5b10ac2561247b1d6272ae937
• https://git.kernel.org/stable/c/5920ac19964f9e20181f63b410d9200ddbf8dc86
• https://git.kernel.org/stable/c/6bd23e0c2bb6c65d4f5754d1456bc9a4427fc59b
• https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html

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