4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> commit 4c4fc90964b1cf205a67df566cc82ea1731bcb00 upstream. 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@xxxxxxxx> Reviewed-by: Ricardo Ribalda <ricardo.ribalda@xxxxxxxxx> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/tty/serial/8250/8250_port.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -1320,7 +1320,7 @@ out_lock: /* * 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) {