From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933184AbXCAJQo (ORCPT ); Thu, 1 Mar 2007 04:16:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933185AbXCAJQo (ORCPT ); Thu, 1 Mar 2007 04:16:44 -0500 Received: from 87-194-8-8.bethere.co.uk ([87.194.8.8]:56953 "EHLO aeryn.fluff.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933184AbXCAJQl (ORCPT ); Thu, 1 Mar 2007 04:16:41 -0500 Date: Thu, 1 Mar 2007 09:16:33 +0000 From: Ben Dooks To: Paul Mundt , linux-kernel@vger.kernel.org, linux-fbdev-devel@lists.sourceforge.net Subject: Re: [PATCH] fb: sm501fb off-by-1 sysfs store Message-ID: <20070301091633.GA21140@fluff.org.uk> References: <20070301082456.GA3701@linux-sh.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070301082456.GA3701@linux-sh.org> X-Disclaimer: These are my own opinions, so there! User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 01, 2007 at 05:24:56PM +0900, Paul Mundt wrote: > Currently sm501fb_crtsrc_store() won't allow the routing to be changed > via echos from userspace in to the sysfs file. The reason for this is > that the strnicmp() for both heads uses a sizeof() for the string length, > which ends up being strlen() + 1 (\0 in the normal case, but the echo > gives a newline, which is where the issue occurs), this then causes a > mismatch and subsequently bails with the -EINVAL. > > In addition to this, the hardcoded lengths were then used for the store > length that was returned, which ended up being erroneous and resulting in > a write error. There's also no point in returning anything but the full > length since it will -EINVAL out on a mismatch well before then anyways. > > sizeof("string") is great for making sure you have space in your buffer, > but rather less so for string comparisons :-) > > Signed-off-by: Paul Mundt Acked-by: Ben Dooks > -- > > drivers/video/sm501fb.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/video/sm501fb.c b/drivers/video/sm501fb.c > index 02b290c..72b5358 100644 > --- a/drivers/video/sm501fb.c > +++ b/drivers/video/sm501fb.c > @@ -1074,9 +1074,9 @@ static ssize_t sm501fb_crtsrc_store(struct device *dev, > if (len < 1) > return -EINVAL; > > - if (strnicmp(buf, "crt", sizeof("crt")) == 0) > + if (strnicmp(buf, "crt", 3) == 0) > head = HEAD_CRT; > - else if (strnicmp(buf, "panel", sizeof("panel")) == 0) > + else if (strnicmp(buf, "panel", 5) == 0) > head = HEAD_PANEL; > else > return -EINVAL; > @@ -1098,7 +1098,7 @@ static ssize_t sm501fb_crtsrc_store(struct device *dev, > writel(ctrl, info->regs + SM501_DC_CRT_CONTROL); > sm501fb_sync_regs(info); > > - return (head == HEAD_CRT) ? 3 : 5; > + return len; > } > > /* Prepare the device_attr for registration with sysfs later */ > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Ben (ben@fluff.org, http://www.fluff.org/) 'a smiley only costs 4 bytes'