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fb: fix fb_pan_display range check

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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>
This commit is contained in:
Florian Tobias Schandinat 2009-09-22 16:47:41 -07:00 committed by Linus Torvalds
parent ff8147fe71
commit 99e9e7d62b
1 changed files with 2 additions and 2 deletions
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4
drivers/video/fbmem.c
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@ -871,8 +871,8 @@ fb_pan_display(struct fb_info *info, struct fb_var_screeninfo *var)
err = -EINVAL; err = -EINVAL;
if (err || !info->fbops->fb_pan_display || if (err || !info->fbops->fb_pan_display ||
var->yoffset + yres > info->var.yres_virtual || var->yoffset > info->var.yres_virtual - yres ||
var->xoffset + info->var.xres > info->var.xres_virtual) var->xoffset > info->var.xres_virtual - info->var.xres)
return -EINVAL; return -EINVAL;
if ((err = info->fbops->fb_pan_display(var, info))) if ((err = info->fbops->fb_pan_display(var, info)))