From: Antonino A. Daplas <adaplas@gmail.com>
Date: Tue, 8 May 2007 07:40:06 +0000 (-0700)
Subject: vgacon: disallow console operations when in KD_GRAPHICS mode
X-Git-Tag: v2.6.22-rc1~369
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2ae854777592856ad8ce4d4cdb6114804e2e28f6;p=pandora-kernel.git

vgacon: disallow console operations when in KD_GRAPHICS mode

Reported by James Pearson as:

	 boot to run level 3

	 if not root, then make sure /dev/console is writeable

	 login and type:

	 setterm -blank 0

	 start X

	 type into an xterm:

	 while true; do echo "" > /dev/console; usleep 100000; done

	 while the above loop is running switch to the text console and back
	 again (Ctrl-Alt-F1 then Ctrl-Alt-F7)

	 ... and the screen will be shifting (and wrapping) to the left.

This problem stems from continuously writing text to the system console (which
is in KD_TEXT mode) while the foreground console is in KD_GRAPHICS
mode. Somewhere along the way, console printing got confused and omitted the
KD_GRAPHICS/KD_TEXT test.  Thus, vgacon attempted to scroll the screen of X,
which causes X to shift.

Fix by disallowing vgacon to touch the hardware when the vc is in KD_GRAPHICS
mode. A definitive fix entails a full audit of the console code.

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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