Commit 99e9e7d6 authored Sep 22, 2009 by Florian Tobias Schandinat Committed by Linus Torvalds Sep 23, 2009

fb: fix fb_pan_display range check



Fix the range check for panning.  The current code fails to detect some
invalid values (very high ones that can occur if an app tries to move
further up/left than 0,0) as the check uses the unknown values for
calculation so that an overflow can occur.

To fix this it is sufficient to move the calculation to the right side to
use only trusted values.

Kai Jiang detected this problem and proposed an initial patch.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Kai Jiang <b18973@freescale.com>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ff8147fe

drivers/video/fbmem.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -871,8 +871,8 @@ fb_pan_display(struct fb_info info, struct fb_var_screeninfo var)
		err = -EINVAL;

		if (err \|\| !info->fbops->fb_pan_display \|\|
		var->yoffset + yres > info->var.yres_virtual \|\|
		var->xoffset + info->var.xres > info->var.xres_virtual)
		var->yoffset > info->var.yres_virtual - yres \|\|
		var->xoffset > info->var.xres_virtual - info->var.xres)
		return -EINVAL;

		if ((err = info->fbops->fb_pan_display(var, info)))

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