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=-5.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, URIBL_DBL_ABUSE_MALW,USER_AGENT_SANE_2 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 DF704C33C9E for ; Fri, 31 Jan 2020 02:05:54 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 842392063A for ; Fri, 31 Jan 2020 02:05:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="UhAHSvWf"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="t/kHqHbI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 842392063A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Date:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=6OJt0rntoLDqZA8RcQE4IPlbKmlzPu9NHZWjNaAO0TY=; b=UhAHSvWf97zPvF iOjzbS4M9oQ4ty+sU9bIQHJrHo1CZqR38CiN827p8Pw2QyUNAb0vHCSXgTNb3mOpI/0bMCvWEZHav XETlqMznQY59KHJc/vfAODFEfbE5ZtJXwJ3IirU8XLmnHAA8pU3S8cqhBlO8BAuOE2v1uWjChfTzb CM/hilViee7iaQc4EHMBo8BOp5+LZbu6HoaWTX3n+79qeywjrGhRdCHgGeJbhSS2NEGdAdXkYRVqe KlPmGBuzWyXzT5JcUFBPy30KWKFGjgbT8zHRF7ED8GkGtFz5XvIrMo6AjrsGV7egHOs+KtfLHn1lG RBgJTynreO5JZ7ExD65A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ixLgs-0007AN-Mq; Fri, 31 Jan 2020 02:05:50 +0000 Received: from mailgw02.mediatek.com ([216.200.240.185]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ixLgp-00079j-Uk; Fri, 31 Jan 2020 02:05:49 +0000 X-UUID: 1b99f470b09443db9ec129b6e29d950d-20200130 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:MIME-Version:Content-Type:References:In-Reply-To:Date:CC:To:From:Subject:Message-ID; bh=eAN7TYSx5Ngnmh1dy1RUM0HJOBtCp5tpJodPVFhl6LQ=; b=t/kHqHbIsMuJDEtefMCvcLTmsW/5c4BBHLrMccFqL+IkVCD9EQGYsUxoeu3xExjhxaeLQeVc6JHic3PR8Th2tLKjUwCDhHw+oOtddmhwkThlVxzRWfvCm6SWd2aIudQTNypgISxPxIiwjIZsMgp3a3SAABvmQQATXNRZhwr6k0Y=; X-UUID: 1b99f470b09443db9ec129b6e29d950d-20200130 Received: from mtkcas66.mediatek.inc [(172.29.193.44)] by mailgw02.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLS) with ESMTP id 919770357; Thu, 30 Jan 2020 18:05:42 -0800 Received: from mtkmbs07n1.mediatek.inc (172.21.101.16) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Thu, 30 Jan 2020 18:05:33 -0800 Received: from mtkcas09.mediatek.inc (172.21.101.178) by mtkmbs07n1.mediatek.inc (172.21.101.16) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Fri, 31 Jan 2020 10:04:23 +0800 Received: from [172.21.84.99] (172.21.84.99) by mtkcas09.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Fri, 31 Jan 2020 10:05:16 +0800 Message-ID: <1580436306.11126.16.camel@mtksdccf07> Subject: Re: [PATCH v3] lib/stackdepot: Fix global out-of-bounds in stackdepot From: Walter Wu To: Alexander Potapenko Date: Fri, 31 Jan 2020 10:05:06 +0800 In-Reply-To: References: <20200130064430.17198-1-walter-zh.wu@mediatek.com> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200130_180547_998924_069104EE X-CRM114-Status: GOOD ( 24.77 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kate Stewart , wsd_upstream , Greg Kroah-Hartman , LKML , linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, Josh Poimboeuf , Matthias Brugger , Thomas Gleixner , Dmitry Vyukov Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 2020-01-30 at 13:03 +0100, Alexander Potapenko wrote: > On Thu, Jan 30, 2020 at 7:44 AM Walter Wu wrote: > > Hi Walter, > > > If the depot_index = STACK_ALLOC_MAX_SLABS - 2 and next_slab_inited = 0, > > then it will cause array out-of-bounds access, so that we should modify > > the detection to avoid this array out-of-bounds bug. > > > > Assume depot_index = STACK_ALLOC_MAX_SLABS - 3 > > Consider following call flow sequence: > > > > stack_depot_save() > > depot_alloc_stack() > > if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) //pass > > depot_index++ //depot_index = STACK_ALLOC_MAX_SLABS - 2 > > if (depot_index + 1 < STACK_ALLOC_MAX_SLABS) //enter > > smp_store_release(&next_slab_inited, 0); //next_slab_inited = 0 > > init_stack_slab() > > if (stack_slabs[depot_index] == NULL) //enter and exit > > > > stack_depot_save() > > depot_alloc_stack() > > if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) //pass > > depot_index++ //depot_index = STACK_ALLOC_MAX_SLABS - 1 > > init_stack_slab(&prealloc) > > stack_slabs[depot_index + 1] //here get global out-of-bounds > > > > Cc: Dmitry Vyukov > > Cc: Matthias Brugger > > Cc: Thomas Gleixner > > Cc: Alexander Potapenko > > Cc: Josh Poimboeuf > > Cc: Kate Stewart > > Cc: Greg Kroah-Hartman > > Cc: Kate Stewart > > Signed-off-by: Walter Wu > > --- > > changes in v2: > > modify call flow sequence and preconditon > > > > changes in v3: > > add some reviewers > > --- > > lib/stackdepot.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/lib/stackdepot.c b/lib/stackdepot.c > > index ed717dd08ff3..7e8a15e41600 100644 > > --- a/lib/stackdepot.c > > +++ b/lib/stackdepot.c > > @@ -106,7 +106,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size, > > required_size = ALIGN(required_size, 1 << STACK_ALLOC_ALIGN); > > > > if (unlikely(depot_offset + required_size > STACK_ALLOC_SIZE)) { > > - if (unlikely(depot_index + 1 >= STACK_ALLOC_MAX_SLABS)) { > > + if (unlikely(depot_index + 2 >= STACK_ALLOC_MAX_SLABS)) { > > I don't think this is the right way to fix the problem. > You're basically throwing away the last element of stack_slabs[], as > we won't allocate anything from it. > ok, I agree. > How about we set |next_slab_inited| to 1 here: > > diff --git a/lib/stackdepot.c b/lib/stackdepot.c > index 2e7d2232ed3c..943a51eb746d 100644 > --- a/lib/stackdepot.c > +++ b/lib/stackdepot.c > @@ -105,6 +105,8 @@ static bool init_stack_slab(void **prealloc) > return true; > if (stack_slabs[depot_index] == NULL) { > stack_slabs[depot_index] = *prealloc; > + if (depot_index + 1 == STACK_ALLOC_MAX_SLABS) > + smp_store_release(&next_slab_inited, 1); > } else { > stack_slabs[depot_index + 1] = *prealloc; > /* > > This will ensure we won't be preallocating pages once |depot_index| > reaches the last element, and we won't attempt to write those pages > anywhere either. > > Could you please check if this fixes the problem for you? > Consider above call flow sequence at first stack_depot_save(), depot_index = STACK_ALLOC_MAX_SLABS - 2 before enter init_stack_slab(), so the fixes should be below. --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -83,6 +83,8 @@ static bool init_stack_slab(void **prealloc) return true; if (stack_slabs[depot_index] == NULL) { stack_slabs[depot_index] = *prealloc; + if (depot_index + 2 == STACK_ALLOC_MAX_SLABS) + smp_store_release(&next_slab_inited, 1); } else { stack_slabs[depot_index + 1] = *prealloc; /* > > WARN_ONCE(1, "Stack depot reached limit capacity"); > > return NULL; > > } > > -- > > 2.18.0 > > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel