From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: [PATCH] serial: 8250: Do nothing if nr_uarts=0 Date: Tue, 05 May 2015 08:26:27 +0200 Message-ID: <55486293.2080400@siemens.com> References: <554797D4.5080704@siemens.com> <5547A614.9020109@hurleysoftware.com> <5547B04C.8080706@siemens.com> <5547C001.8040400@hurleysoftware.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5547C001.8040400@hurleysoftware.com> Sender: linux-kernel-owner@vger.kernel.org To: Greg Kroah-Hartman Cc: Peter Hurley , Linux Kernel Mailing List , linux-serial@vger.kernel.org List-Id: linux-serial@vger.kernel.org When nr_uarts was set to 0 (via config or 8250_core.nr_uarts), we crash early on x86 because serial8250_isa_init_ports dereferences base_ops which remains NULL. In fact, there is nothing to do for all the callers of serial8250_isa_init_ports if there are no uarts. Based on suggestions by Peter Hurley. Signed-off-by: Jan Kiszka --- This supersedes "serial: 8250: Prevent kernel crash with nr_uarts=0" drivers/tty/serial/8250/8250_core.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 4506e40..dfcb14f 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -3548,6 +3548,9 @@ static struct console univ8250_console = { static int __init univ8250_console_init(void) { + if (nr_uarts == 0) + return -ENODEV; + serial8250_isa_init_ports(); register_console(&univ8250_console); return 0; @@ -3578,7 +3581,7 @@ int __init early_serial_setup(struct uart_port *port) { struct uart_port *p; - if (port->line >= ARRAY_SIZE(serial8250_ports)) + if (port->line >= ARRAY_SIZE(serial8250_ports) || nr_uarts == 0) return -ENODEV; serial8250_isa_init_ports(); @@ -3945,6 +3948,9 @@ static int __init serial8250_init(void) { int ret; + if (nr_uarts == 0) + return -ENODEV; + serial8250_isa_init_ports(); printk(KERN_INFO "Serial: 8250/16550 driver, " -- 2.1.4