[SRU][J][PATCH 0/1] CVE-2024-50073

[Massimiliano Pellizzer]

https://ubuntu.com/security/CVE-2024-50073

[ Impact ]

tty: n_gsm: Fix use-after-free in gsm_cleanup_mux

gsm_msg on the tx_ctrl_list or tx_data_list of gsm_mux
can be freed by multi threads through ioctl,which leads
to the occurrence of uaf. Protect it by gsm tx lock.

[ Fix ]

Plucky: not affected
Noble: fixed via upstream stable updates (LP: #2097393)
Jammy: fix backported from mainline

[ Test Plan ]

Compile tested only.

[ Where Problems Could Occur ]

The fix affects the GSM 07.10 multiplexer line discipline in the TTY subsystem.
An issue with this fix may introduce problems such as improper acquisition
or release of the tx_lock spinlock, potentially resulting in deadlocks during
multiplexer teardown or data transmission.
As a consequence, regular users may experience hangs or stalls in applications
communicating over GSM virtual TTYs.