linux-kernel - [PATCH] serial: 8250: Prevent kernel crash with nr

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Message-ID: <554797D4.5080704@siemens.com>
Date:	Mon, 04 May 2015 18:01:24 +0200
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-serial@...r.kernel.org
Subject: [PATCH] serial: 8250: Prevent kernel crash with nr_uarts=0

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 that function if
there are no uarts.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
---
 drivers/tty/serial/8250/8250_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 4506e40..e1363a40 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -3256,7 +3256,7 @@ static void __init serial8250_isa_init_ports(void)
 	static int first = 1;
 	int i, irqflag = 0;
 
-	if (!first)
+	if (!first || nr_uarts == 0)
 		return;
 	first = 0;
 
-- 
2.1.4
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