From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75430C2B9F4 for ; Mon, 14 Jun 2021 23:14:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B796611BE for ; Mon, 14 Jun 2021 23:14:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229760AbhFNXQp (ORCPT ); Mon, 14 Jun 2021 19:16:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58812 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229734AbhFNXQp (ORCPT ); Mon, 14 Jun 2021 19:16:45 -0400 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ED901C061574 for ; Mon, 14 Jun 2021 16:14:41 -0700 (PDT) Received: by fieldses.org (Postfix, from userid 2815) id 06FE86814; Mon, 14 Jun 2021 19:14:41 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 06FE86814 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1623712481; bh=5mx/UpsjnshyzHxrnY65bNR7Yp+7xLz2y67iIKPjaaI=; h=Date:To:Cc:Subject:References:In-Reply-To:From:From; b=I6pWDKqltPMfoZFGTzg6My+N1b95Hmnwk71RA+DlaNoS5yAhWSCi8Jn8/+EjSdsFx akCAvIUjFrpeDqkDojpQZ67+LSRj3BMkq2hW91Hps8N4QpIfQy3usJ156wBBOMXRSn NvMRpQstVhhHq1cBGA5rXioNy7RIlMa7WwuMOHH4= Date: Mon, 14 Jun 2021 19:14:40 -0400 To: schumaker.anna@gmail.com Cc: Trond.Myklebust@hammerspace.com, linux-nfs@vger.kernel.org, Anna.Schumaker@Netapp.com Subject: Re: [PATCH] sunrpc: Avoid a KASAN slab-out-of-bounds bug in xdr_set_page_base() Message-ID: <20210614231440.GD16500@fieldses.org> References: <20210609210729.254578-1-Anna.Schumaker@Netapp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210609210729.254578-1-Anna.Schumaker@Netapp.com> User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Wed, Jun 09, 2021 at 05:07:29PM -0400, schumaker.anna@gmail.com wrote: > From: Anna Schumaker > > This seems to happen fairly easily during READ_PLUS testing on NFS v4.2. Yep, I hit a KASAN warning here every time, and this fixes it, thanks.--b. > I found that we could end up accessing xdr->buf->pages[pgnr] with a pgnr > greater than the number of pages in the array. So let's just return > early if we're setting base to a point at the end of the page data and > let xdr_set_tail_base() handle setting up the buffer pointers instead. > > Signed-off-by: Anna Schumaker > --- > net/sunrpc/xdr.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c > index 3964ff74ee51..ca10ba2626f2 100644 > --- a/net/sunrpc/xdr.c > +++ b/net/sunrpc/xdr.c > @@ -1230,10 +1230,9 @@ static unsigned int xdr_set_page_base(struct xdr_stream *xdr, > void *kaddr; > > maxlen = xdr->buf->page_len; > - if (base >= maxlen) { > - base = maxlen; > - maxlen = 0; > - } else > + if (base >= maxlen) > + return 0; > + else > maxlen -= base; > if (len > maxlen) > len = maxlen; > -- > 2.32.0