From owner-svn-src-all@FreeBSD.ORG  Fri Mar 20 11:08:57 2009
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id CC650106566B;
	Fri, 20 Mar 2009 11:08:57 +0000 (UTC) (envelope-from kib@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:4f8:fff6::2c])
	by mx1.freebsd.org (Postfix) with ESMTP id BA6428FC08;
	Fri, 20 Mar 2009 11:08:57 +0000 (UTC) (envelope-from kib@FreeBSD.org)
Received: from svn.freebsd.org (localhost [127.0.0.1])
	by svn.freebsd.org (8.14.3/8.14.3) with ESMTP id n2KB8vwO000503;
	Fri, 20 Mar 2009 11:08:57 GMT (envelope-from kib@svn.freebsd.org)
Received: (from kib@localhost)
	by svn.freebsd.org (8.14.3/8.14.3/Submit) id n2KB8vHN000502;
	Fri, 20 Mar 2009 11:08:57 GMT (envelope-from kib@svn.freebsd.org)
Message-Id: <200903201108.n2KB8vHN000502@svn.freebsd.org>
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Fri, 20 Mar 2009 11:08:57 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
	svn-src-head@freebsd.org
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Cc: 
Subject: svn commit: r190145 - head/sys/kern
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
	user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
	<mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 20 Mar 2009 11:08:58 -0000

Author: kib
Date: Fri Mar 20 11:08:57 2009
New Revision: 190145
URL: http://svn.freebsd.org/changeset/base/190145

Log:
  Do not underflow the buffer and then report the problem. Check for the
  condition before the buffer write.
  Also, since buflen is unsigned, previous check was ignored.
  
  Reviewed by:	marcus
  Tested by:	pho

Modified:
  head/sys/kern/vfs_cache.c

Modified: head/sys/kern/vfs_cache.c
==============================================================================
--- head/sys/kern/vfs_cache.c	Fri Mar 20 11:03:55 2009	(r190144)
+++ head/sys/kern/vfs_cache.c	Fri Mar 20 11:08:57 2009	(r190145)
@@ -970,13 +970,13 @@ vn_fullpath1(struct thread *td, struct v
 			if (error)
 				return (error);
 		}
-		*--bp = '/';
-		buflen--;
-		if (buflen < 0) {
+		if (buflen <= 0) {
 			numfullpathfail4++;
 			CACHE_RUNLOCK();
 			return (ENOMEM);
 		}
+		*--bp = '/';
+		buflen--;
 		slash_prefixed = 1;
 	}
 	while (vp != rdir && vp != rootvnode) {
@@ -1013,14 +1013,14 @@ vn_fullpath1(struct thread *td, struct v
 			if (error)
 				break;
 		}
-		*--bp = '/';
-		buflen--;
-		if (buflen < 0) {
+		if (buflen <= 0) {
 			numfullpathfail4++;
 			CACHE_RUNLOCK();
 			error = ENOMEM;
 			break;
 		}
+		*--bp = '/';
+		buflen--;
 		slash_prefixed = 1;
 	}
 	if (error)