serial: mxs-auart: add spinlock around changing cts state

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: serial: mxs-auart: add spinlock around changing cts state The uart_handle_cts_change() function in serial_core expects the caller to hold uport->lock. For example, I have seen the below kernel splat, when the Bluetooth driver is loaded on an i.MX28 board. [ 85.119255] ------------[ cut here ]------------ [ 85.124413] WARNING: CPU: 0 PID: 27 at /drivers/tty/serial/serial_core.c:3453 uart_handle_cts_change+0xb4/0xec [ 85.134694] Modules linked in: hci_uart bluetooth ecdh_generic ecc wlcore_sdio configfs [ 85.143314] CPU: 0 PID: 27 Comm: kworker/u3:0 Not tainted 6.6.3-00021-gd62a2f068f92 #1 [ 85.151396] Hardware name: Freescale MXS (Device Tree) [ 85.156679] Workqueue: hci0 hci_power_on [bluetooth] (...) [ 85.191765] uart_handle_cts_change from mxs_auart_irq_handle+0x380/0x3f4 [ 85.198787] mxs_auart_irq_handle from __handle_irq_event_percpu+0x88/0x210 (...)

References

• https://git.kernel.org/stable/c/56434e295bd446142025913bfdf1587f5e1970ad
• https://git.kernel.org/stable/c/21535ef0ac1945080198fe3e4347ea498205c99a
• https://git.kernel.org/stable/c/0dc0637e6b16158af85945425821bfd0151adb37
• https://git.kernel.org/stable/c/479244d68f5d94f3903eced52b093c1e01ddb495
• https://git.kernel.org/stable/c/2c9b943e9924cf1269e44289bc5e60e51b0f5270
• https://git.kernel.org/stable/c/5f40fd6ca2cf0bfbc5a5c9e403dfce8ca899ba37
• https://git.kernel.org/stable/c/94b0e65c75f4af888ab2dd6c90f060f762924e86
• https://git.kernel.org/stable/c/54c4ec5f8c471b7c1137a1f769648549c423c026