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

stable inclusion
from stable-v4.19.316
commit 44b38924135d2093e2ec1812969464845dd66dc9
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA7D3L
CVE: CVE-2024-38634

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=44b38924135d2093e2ec1812969464845dd66dc9



--------------------------------

[ Upstream commit 77ab53371a2066fdf9b895246505f5ef5a4b5d47 ]

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]

Fixes: 7831d56b ("tty: MAX3100")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240402195306.269276-2-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yi Yang <yiyang13@huawei.com>