linux-kernel - [PATCH 1/1] TTY: fix keyboard crash

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Date:	Mon, 12 Mar 2012 16:23:02 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	gregkh@...uxfoundation.org
Cc:	linux-kernel@...r.kernel.org, jirislaby@...il.com,
	Alan Cox <alan@...ux.intel.com>
Subject: [PATCH 1/1] TTY: fix keyboard crash

I get this during bootup:
BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffff81301a59>] vt_do_kdsk_ioctl+0x2b9/0x3b0
...
Call Trace:
 [<ffffffff812fcbc0>] vt_ioctl+0xce0/0x12f0
 [<ffffffff812f2b1c>] tty_ioctl+0x28c/0xbe0
...

It is due to mistake in commit "vt:tackle kbd_table". It moves the
allocation to be away from the atomic section, but omits to set
key_map to the new pointer properly.

So do it here and now.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Cc: Alan Cox <alan@...ux.intel.com>
---
 drivers/tty/vt/keyboard.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index 70d0593..269c6c9 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -1862,7 +1862,7 @@ int vt_do_kdsk_ioctl(int cmd, struct kbentry __user *user_kbe, int perm,
 				kfree(new_map);
 				return -EPERM;
 			}
-			key_maps[s] = new_map;
+			key_map = key_maps[s] = new_map;
 			key_map[0] = U(K_ALLOCATED);
 			for (j = 1; j < NR_KEYS; j++)
 				key_map[j] = U(K_HOLE);
-- 
1.7.9.2


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