From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roel Kluin Subject: Re: fbcmap: non working tests on unsigned cmap->start Date: Sun, 26 Apr 2009 14:20:47 +0200 Message-ID: <49F4519F.4090003@gmail.com> References: <49EDD799.8060607@gmail.com> <20090423134110.51ea8df2.akpm@linux-foundation.org> <20090423214738.GF7134@sci.fi> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sfi-mx-4.v28.ch3.sourceforge.com ([172.29.28.124] helo=mx.sourceforge.net) by 235xhf1.ch3.sourceforge.com with esmtp (Exim 4.69) (envelope-from ) id 1Ly3M1-0002Mw-0A for linux-fbdev-devel@lists.sourceforge.net; Sun, 26 Apr 2009 12:21:05 +0000 Received: from mail-ew0-f217.google.com ([209.85.219.217]) by 1b2kzd1.ch3.sourceforge.com with esmtp (Exim 4.69) id 1Ly3Lm-0005tR-1k for linux-fbdev-devel@lists.sourceforge.net; Sun, 26 Apr 2009 12:20:54 +0000 Received: by ewy17 with SMTP id 17so1723678ewy.10 for ; Sun, 26 Apr 2009 05:20:47 -0700 (PDT) In-Reply-To: <20090423214738.GF7134@sci.fi> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-fbdev-devel-bounces@lists.sourceforge.net To: Andrew Morton , Roel Kluin , linux-fbdev-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, adaplas@gmail.com cmap->start is unsigned, A negative start could result in incorrect colors. `start' is used as the starting index for the hardware palette, 'start+len-1' is the last index. Signed-off-by: Roel Kluin --- >>> vi include/linux/fb.h +478 >>> >>> Note that struct fb_cmap_user cmap->start in fb_set_user_cmap() is unsigned. >>> Should there maybe be a test: >>> >>> if (cmap->start > MAX || ...) >>> >>> (and what should MAX be then?) >>> > On Thu, Apr 23, 2009 at 01:41:10PM -0700, Andrew Morton wrote: >> argh. >> >> - Perhaps userspace can kill the kernel by sending a "negative" >> `start'. Removing the test will make it even less likely that we'll >> fix this bug. > > Shouldn't happen. 'start' is used as the starting index for the hardware > palette, 'start+len-1' is the last index. All drivers should already check > the passed values since the maximum index depends on the display mode. > And I suppose the worst thing that could happen if the driver fails to > check the values would be incorrect colors. Thanks for your explanation, I think this should fix it? diff --git a/drivers/video/fbcmap.c b/drivers/video/fbcmap.c index f53b9f1..ea62d87 100644 --- a/drivers/video/fbcmap.c +++ b/drivers/video/fbcmap.c @@ -266,7 +266,7 @@ int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info) rc = -ENODEV; goto out; } - if (cmap->start < 0 || (!info->fbops->fb_setcolreg && + if (cmap->start >= cmap->len || (!info->fbops->fb_setcolreg && !info->fbops->fb_setcmap)) { rc = -EINVAL; goto out1; ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensign option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects