Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932220AbVILUl3 (ORCPT ); Mon, 12 Sep 2005 16:41:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932227AbVILUl2 (ORCPT ); Mon, 12 Sep 2005 16:41:28 -0400 Received: from [66.228.95.230] ([66.228.95.230]:21635 "EHLO postage-due.permabit.com") by vger.kernel.org with ESMTP id S932220AbVILUl1 (ORCPT ); Mon, 12 Sep 2005 16:41:27 -0400 To: Valdis.Kletnieks@vt.edu Cc: linux-kernel@vger.kernel.org, marcelo.tosatti@cyclades.com 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> From: Assar Date: 12 Sep 2005 16:41:19 -0400 In-Reply-To: <200509122001.j8CK1kpW028651@turing-police.cc.vt.edu> Message-ID: <788xy2qas0.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: 1867 Lines: 42 Valdis.Kletnieks@vt.edu writes: > > To my reading, the 2.6.13 code does not copy the 4 bytes of length to > > rcvbuf. > > Hmm... it still does this: > kaddr[len+rcvbuf->page_base] = '\0'; > which still has a possible off-by-one? (Was that why you have -1 -4?) The check is different. 2.6.13 is using ">=" instead of ">", so hence I think that's fine. > sizeof(actual_var) is even better, as that way it's clear what you're allowing > space for. 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 2005-09-12 16:12:30.000000000 -0400 @@ -571,8 +571,8 @@ 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(*strlen) - 1) + len = rcvbuf->page_len - sizeof(*strlen) - 1; *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 2005-09-12 16:12:29.000000000 -0400 @@ -759,8 +759,8 @@ 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(*strlen) - 1) + len = rcvbuf->page_len - sizeof(*strlen) - 1; *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/