Bug 1227886 (CVE-2024-40966)

Summary: VUL-0: CVE-2024-40966: kernel: tty: add the option to have a tty reject a new ldisc
Product: [Novell Products] SUSE Security Incidents Reporter: SMASH SMASH <smash_bz>
Component: IncidentsAssignee: Kernel Bugs <kernel-bugs>
Status: NEW --- QA Contact: Security Team bot <security-team>
Severity: Normal    
Priority: P3 - Medium CC: andrea.mattiazzo
Version: unspecified   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/413893/
Whiteboard: CVSSv3.1:SUSE:CVE-2024-40966:4.7:(AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H)
Found By: Security Response Team Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description SMASH SMASH 2024-07-16 07:58:10 UTC 
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.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2024-40966
https://www.cve.org/CVERecord?id=CVE-2024-40966
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/pub/scm/linux/security/vulns.git/plain/cve/published/2024/CVE-2024-40966.mbox