4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior bigeasy@linutronix.de
commit 9594b5be7ec110ed11acec58fa94f3f293668c85 upstream.
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
--- drivers/tty/serial/atmel_serial.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
--- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -1803,7 +1803,6 @@ static int atmel_startup(struct uart_por { 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;
/* @@ -1818,8 +1817,8 @@ static int atmel_startup(struct uart_por * 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;