linux-kernel - RE: [PATCH 12/32] Blackfin arch: Fix bug using usb keyboard crashes kernel

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Date:	Mon, 21 May 2007 13:07:05 +0100
From:	"Hennerich, Michael" <Michael.Hennerich@...log.com>
To:	"Pekka Enberg" <penberg@...helsinki.fi>,
	"Bryan Wu" <bryan.wu@...log.com>
Cc:	<torvalds@...ux-foundation.org>, <akpm@...ux-foundation.org>,
	<linux-kernel@...r.kernel.org>,
	"Michael Hennerich" <michael.hennerich@...log.com>
Subject: RE: [PATCH 12/32] Blackfin arch: Fix bug using usb keyboard crashes kernel

I was fixing this issue some time ago.

With CONFIG_VT (drivers/char/vt.c) enabled and a USB HID keyboard connected, we were seeing bad pointer dereferences in drivers/char/keyboard.c

In function kbd_keycode vc_cons[fg_console].d was un-initialized .

static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
{
--snip--
	struct vc_data *vc = vc_cons[fg_console].d;

--snip--
	tty = vc->vc_tty;
--snip--
}	

The workaround, almost any arch does is to initialize conswitchp with the dummy console.

conswitchp = &dummy_con;	

The dummy console gets automatically selected if there is no other suitable console (VGA).
The bit we were missing is simply this fix.

Best regards,
Michael


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>-----Original Message-----
>From: penberg@...il.com [mailto:penberg@...il.com] On Behalf Of Pekka
>Enberg
>Sent: Montag, 21. Mai 2007 13:40
>To: Bryan Wu
>Cc: torvalds@...ux-foundation.org; akpm@...ux-foundation.org; linux-
>kernel@...r.kernel.org; Michael Hennerich
>Subject: Re: [PATCH 12/32] Blackfin arch: Fix bug using usb keyboard
>crashes kernel
>
>Hi Bryan,
>
>On 5/21/07, Bryan Wu <bryan.wu@...log.com> wrote:
>> +#ifdef CONFIG_DUMMY_CONSOLE
>> +       conswitchp = &dummy_con;
>> +#endif
>>         cclk = get_cclk();
>>         sclk = get_sclk();
>
>This patch has no changelog. While it is probably apparent to you why
>this fixes a crash when using an USB keyboard, it would be nice for
>the rest of us to know which crash it fixes and why.
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