Vulnerability CVE-2024-40966
Published: 2024-07-12

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.

 References:
https://git.kernel.org/stable/c/3c6332f3bb1578b5b10ac2561247b1d6272ae937
https://git.kernel.org/stable/c/287b569a5b914903ba7c438a3c0dbc3410ebb409
https://git.kernel.org/stable/c/5920ac19964f9e20181f63b410d9200ddbf8dc86
https://git.kernel.org/stable/c/6bd23e0c2bb6c65d4f5754d1456bc9a4427fc59b
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