Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932668AbVINVCc (ORCPT ); Wed, 14 Sep 2005 17:02:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932758AbVINVCc (ORCPT ); Wed, 14 Sep 2005 17:02:32 -0400 Received: from [66.228.95.230] ([66.228.95.230]:58041 "EHLO postage-due.permabit.com") by vger.kernel.org with ESMTP id S932668AbVINVCb (ORCPT ); Wed, 14 Sep 2005 17:02:31 -0400 To: Peter Staubach Cc: Marcelo Tosatti , Trond Myklebust , Valdis.Kletnieks@vt.edu, linux-kernel@vger.kernel.org Subject: Re: [PATCH] nfs client, kernel 2.4.31: readlink result overflow References: <78irx6wh6j.fsf@sober-counsel.permabit.com> <200509121846.j8CIk5YE025124@turing-police.cc.vt.edu> <784q8qrsad.fsf@sober-counsel.permabit.com> <200509122001.j8CK1kpW028651@turing-police.cc.vt.edu> <788xy2qas0.fsf@sober-counsel.permabit.com> <20050913183948.GE14889@dmt.cnet> <784q8okdfn.fsf@sober-counsel.permabit.com> <20050913193539.GB17222@dmt.cnet> <784q8oivp4.fsf@sober-counsel.permabit.com> <43287221.8020602@redhat.com> <7864t3h1xw.fsf@sober-counsel.permabit.com> <432884CE.9060506@redhat.com> <78r7brflb0.fsf@sober-counsel.permabit.com> <432887C8.2000607@redhat.com> From: Assar Date: 14 Sep 2005 16:59:25 -0400 In-Reply-To: <432887C8.2000607@redhat.com> Message-ID: <78irx3fjrm.fsf@sober-counsel.permabit.com> User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/20.7 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Permabit-Spam: SKIPPED Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1868 Lines: 42 Peter Staubach writes: > Understand. I would recommend that the 2.4 kernel be modified to return > an error, since we are already modifying the area anyway. Marcelo: what's your thought? If you want to go that route, the patch below should do it. diff -u linux-2.4.31.orig/fs/nfs/nfs2xdr.c linux-2.4.31/fs/nfs/nfs2xdr.c --- linux-2.4.31.orig/fs/nfs/nfs2xdr.c 2002-11-28 18:53:15.000000000 -0500 +++ linux-2.4.31/fs/nfs/nfs2xdr.c 2005-09-14 16:57:21.000000000 -0400 @@ -571,8 +571,11 @@ strlen = (u32*)kmap(rcvbuf->pages[0]); /* Convert length of symlink */ len = ntohl(*strlen); - if (len > rcvbuf->page_len) - len = rcvbuf->page_len; + if (len >= rcvbuf->page_len - sizeof(u32) || len > NFS2_MAXPATHLEN) { + printk(KERN_WARNING "NFS: server returned giant symlink!\n"); + kunmap(rcvbuf->pages[0]); + return -ENAMETOOLONG; + } *strlen = len; /* NULL terminate the string we got */ string = (char *)(strlen + 1); diff -u linux-2.4.31.orig/fs/nfs/nfs3xdr.c linux-2.4.31/fs/nfs/nfs3xdr.c --- linux-2.4.31.orig/fs/nfs/nfs3xdr.c 2003-11-28 13:26:21.000000000 -0500 +++ linux-2.4.31/fs/nfs/nfs3xdr.c 2005-09-14 16:57:37.000000000 -0400 @@ -759,8 +759,11 @@ strlen = (u32*)kmap(rcvbuf->pages[0]); /* Convert length of symlink */ len = ntohl(*strlen); - if (len > rcvbuf->page_len) - len = rcvbuf->page_len; + if (len >= rcvbuf->page_len - sizeof(u32)) { + printk(KERN_WARNING "NFS: server returned giant symlink!\n"); + kunmap(rcvbuf->pages[0]); + return -ENAMETOOLONG; + } *strlen = len; /* NULL terminate the string we got */ string = (char *)(strlen + 1); - 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/