patch "drivers/tty: 8250: only call fintek_8250_probe when doing port I/O" added to tty-linus

[<gregkh@linuxfoundation.org>]

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

    drivers/tty: 8250: only call fintek_8250_probe when doing port I/O

to my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 4c4fc90964b1cf205a67df566cc82ea1731bcb00 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Thu, 18 May 2017 12:29:55 +0100
Subject: drivers/tty: 8250: only call fintek_8250_probe when doing port I/O

Commit fa01e2ca9f53 ("serial: 8250: Integrate Fintek into 8250_base")
modified the probing logic for PNP0501 devices, to remove a collision
between the generic 16550A driver and the Fintek driver, which reused
the same ACPI _HID.

The Fintek device probe is now incorporated into the common 8250 probe
path, and gets called for all discovered 16550A compatible devices,
including ones that are MMIO mapped rather than IO mapped. However,
the Fintek driver assumes the port base is a I/O address, and proceeds
to probe some arbitrary offsets above it.

This is generally a wrong thing to do, but on ARM systems (having no
native port I/O), this may result in faulting accesses of completely
unrelated MMIO regions in the PCI I/O space. Given that this is at
serial probe time, this results in hard to diagnose crashes at boot.

So let's restrict the Fintek probe to devices that we know are using
port I/O in the first place.

Fixes: fa01e2ca9f53 ("serial: 8250: Integrate Fintek into 8250_base")
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Ricardo Ribalda <ricardo.ribalda@gmail.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/8250/8250_port.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 09a65a3ec7f7..e7765f010fe8 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1337,7 +1337,7 @@ static void autoconfig(struct uart_8250_port *up)
 	/*
 	 * Check if the device is a Fintek F81216A
 	 */
-	if (port->type == PORT_16550A)
+	if (port->type == PORT_16550A && port->iotype == UPIO_PORT)
 		fintek_8250_probe(up);
 
 	if (up->capabilities != old_capabilities) {
-- 
2.13.0