Patch "serial: core: mark port as initialized after successful IRQ change" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    serial: core: mark port as initialized after successful IRQ change

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     serial-core-mark-port-as-initialized-after-successful-irq-change.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 44117a1d1732c513875d5a163f10d9adbe866c08 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 11 Jan 2018 18:57:26 +0100
Subject: serial: core: mark port as initialized after successful IRQ change

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

commit 44117a1d1732c513875d5a163f10d9adbe866c08 upstream.

setserial changes the IRQ via uart_set_info(). It invokes
uart_shutdown() which free the current used IRQ and clear
TTY_PORT_INITIALIZED. It will then update the IRQ number and invoke
uart_startup() before returning to the caller leaving
TTY_PORT_INITIALIZED cleared.

The next open will crash with
|  list_add double add: new=ffffffff839fcc98, prev=ffffffff839fcc98, next=ffffffff839fcc98.
since the close from the IOCTL won't free the IRQ (and clean the list)
due to the TTY_PORT_INITIALIZED check in uart_shutdown().

There is same pattern in uart_do_autoconfig() and I *think* it also
needs to set TTY_PORT_INITIALIZED there.
Is there a reason why uart_startup() does not set the flag by itself
after the IRQ has been acquired (since it is cleared in uart_shutdown)?

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/tty/serial/serial_core.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -965,6 +965,8 @@ static int uart_set_info(struct tty_stru
 		}
 	} else {
 		retval = uart_startup(tty, state, 1);
+		if (retval == 0)
+			tty_port_set_initialized(port, true);
 		if (retval > 0)
 			retval = 0;
 	}


Patches currently in stable-queue which might be from bigeasy@linutronix.de are

queue-4.9/serial-core-mark-port-as-initialized-after-successful-irq-change.patch