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tty/serial: atmel: use port->name as name in request_irq()

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I was puzzled while looking at /proc/interrupts and random things showed
up between reboots. This occurred more often but I realised it later. The
"correct" output should be:
|38:      11861  atmel-aic5   2 Level     ttyS0

but I saw sometimes
|38:       6426  atmel-aic5   2 Level     tty1

and accounted it wrongly as correct. This is use after free and the
former example randomly got the "old" pointer which pointed to the same
content. With SLAB_FREELIST_RANDOM and HARDENED I even got
|38:       7067  atmel-aic5   2 Level     E=Started User Manager for UID 0

or other nonsense.
As it turns out the tty, pointer that is accessed in atmel_startup(), is
freed() before atmel_shutdown(). It seems to happen quite often that the
tty for ttyS0 is allocated and freed while ->shutdown is not invoked. I
don't do anything special - just a systemd boot :)

Use dev_name(&pdev->dev) as the IRQ name for request_irq(). This exists
as long as the driver is loaded so no use-after-free here.

Cc: stable@vger.kernel.org
Fixes: 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close")
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2018-05-07 19:11:30 +02:00 committed by Greg Kroah-Hartman
parent 7722c24091
commit 9594b5be7e
1 changed files with 2 additions and 3 deletions
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5
drivers/tty/serial/atmel_serial.c
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@ -1757,7 +1757,6 @@ static int atmel_startup(struct uart_port *port)
{
struct platform_device *pdev = to_platform_device(port->dev);
struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
struct tty_struct *tty = port->state->port.tty;
int retval;
/*
@ -1772,8 +1771,8 @@ static int atmel_startup(struct uart_port *port)
* Allocate the IRQ
*/
retval = request_irq(port->irq, atmel_interrupt,
IRQF_SHARED | IRQF_COND_SUSPEND,
tty ? tty->name : "atmel_serial", port);
IRQF_SHARED | IRQF_COND_SUSPEND,
dev_name(&pdev->dev), port);
if (retval) {
dev_err(port->dev, "atmel_startup - Can't get irq\n");
return retval;