serial: max3100: Lock port->lock when calling uart_handle_cts_change()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: serial: max3100: Lock port->lock when calling uart_handle_cts_change() uart_handle_cts_change() has to be called with port lock taken, Since we run it in a separate work, the lock may not be taken at the time of running. Make sure that it's taken by explicitly doing that. Without it we got a splat: WARNING: CPU: 0 PID: 10 at drivers/tty/serial/serial_core.c:3491 uart_handle_cts_change+0xa6/0xb0 ... Workqueue: max3100-0 max3100_work [max3100] RIP: 0010:uart_handle_cts_change+0xa6/0xb0 ... max3100_handlerx+0xc5/0x110 [max3100] max3100_work+0x12a/0x340 [max3100]

References

• https://git.kernel.org/stable/c/44b38924135d2093e2ec1812969464845dd66dc9
• https://git.kernel.org/stable/c/ea9b35372b58ac2931bfc1d5bc25e839d1221e30
• https://git.kernel.org/stable/c/cc121e3722a0a2c8f716ef991e5425b180a5fb94
• https://git.kernel.org/stable/c/78dbda51bb4241b88a52d71620f06231a341f9ba
• https://git.kernel.org/stable/c/8296bb9e5925b6634259c5d4daee88f0cc0884ec
• https://git.kernel.org/stable/c/93df2fba6c7dfa9a2f08546ea9a5ca4728758458
• https://git.kernel.org/stable/c/865b30c8661924ee9145f442bf32cea549faa869
• https://git.kernel.org/stable/c/77ab53371a2066fdf9b895246505f5ef5a4b5d47