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=-11.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 F0943C433E6 for ; Tue, 1 Sep 2020 20:54:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1DFB2078B for ; Tue, 1 Sep 2020 20:54:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="eELfQzbS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727851AbgIAUyY (ORCPT ); Tue, 1 Sep 2020 16:54:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726091AbgIAUyX (ORCPT ); Tue, 1 Sep 2020 16:54:23 -0400 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19E6AC061244; Tue, 1 Sep 2020 13:54:22 -0700 (PDT) Received: by mail-pf1-x444.google.com with SMTP id m8so1542295pfh.3; Tue, 01 Sep 2020 13:54:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=FRTR1pQ5xaQZ2uOprnJ9rvvshbUxSZlhlKoxnO7URRM=; b=eELfQzbSGjuv8KyOMVHl+sTrzSe3ziixFesUVCgWOu7/Z9muIvFP7Bi4DRJZMs6RcJ uhMvWISw8EQN1/7gxRmFAFsNBG5Sh9QbZV6QgcFDjmSpu/uuHUY9boYcGOBpACpZ2QKm 2xrLnc3Zu6wcDZtzf6kTWiFrA/YhL2qcA9RPBXgRzmQs/uy/H7Jn+SzylyQeVuoHjASv vAVeYbXCILJrBBwG1cAuMAGgHRm6simSr4if2kYJM3hqSroABMSvzIJAMe0A2WueufHt t5wBEp5mZqpgLu3vzcoJLecspOTik/9RM6BJkEqtdcJgnSSWtV2vjAN/aVdEovSHd2Tj jceg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=FRTR1pQ5xaQZ2uOprnJ9rvvshbUxSZlhlKoxnO7URRM=; b=N5aNCXzxJApOPZFxE4JGLzB6qJYXuGF2hBysLwgYBRO0rMQLtkR5JMIM4tBdOsM9u6 R05VHXGifDA9tjY9aSxNRt06ZcqvyJm0LQtWHS2QihRFCKLmf0yR8hyrWOHVF11dBLKk CK3xj6M017lQcXyQM9lInXZhLEBd86YFdVsJh1aPUtvmwIMp4KkwvTfUQoGmZVEX+/n9 Jck4BRaxSITI7vxUNATMP2XxDJ/aOLZDLWsSLJYf6c3W98rLlOcUQLXHLHjY2Dh5vqHH btVzDhBru9ZC0fNcku3cL8CVQS6NgVySlRyhb4WABlDoJzy8jLTQm88oNQHpj7/gYk4g 292g== X-Gm-Message-State: AOAM531aw/rl0fXU/RIE2O7CVcyV6csCx6lLGeSpu7ZTkNav71UdcbbY ZeIkpYqTdxJKS5Zwmeywrlw= X-Google-Smtp-Source: ABdhPJybz8lKswfhAONDTigR0brpOOZSb0wvBo43ZZyZYaJi6PxdmqR6MUqDZmJI2ioaYEYqLLibGw== X-Received: by 2002:a63:384b:: with SMTP id h11mr3124012pgn.113.1598993661459; Tue, 01 Sep 2020 13:54:21 -0700 (PDT) Received: from Asurada-Nvidia (thunderhill.nvidia.com. [216.228.112.22]) by smtp.gmail.com with ESMTPSA id y1sm3016263pgr.3.2020.09.01.13.54.20 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 01 Sep 2020 13:54:21 -0700 (PDT) Date: Tue, 1 Sep 2020 13:53:47 -0700 From: Nicolin Chen To: Michael Ellerman Cc: benh@kernel.crashing.org, paulus@samba.org, rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, tony.luck@intel.com, fenghua.yu@intel.com, schnelle@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, sfr@canb.auug.org.au, hch@lst.de, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-parisc@vger.kernel.org Subject: Re: [RESEND][PATCH 1/7] powerpc/iommu: Avoid overflow at boundary_size Message-ID: <20200901205346.GA17362@Asurada-Nvidia> References: <20200831203811.8494-1-nicoleotsuka@gmail.com> <20200831203811.8494-2-nicoleotsuka@gmail.com> <87lfht1vav.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87lfht1vav.fsf@mpe.ellerman.id.au> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Tue, Sep 01, 2020 at 11:27:36PM +1000, Michael Ellerman wrote: > Nicolin Chen writes: > > The boundary_size might be as large as ULONG_MAX, which means > > that a device has no specific boundary limit. So either "+ 1" > > or passing it to ALIGN() would potentially overflow. > > > > According to kernel defines: > > #define ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask)) > > #define ALIGN(x, a) ALIGN_MASK(x, (typeof(x))(a) - 1) > > > > We can simplify the logic here: > > ALIGN(boundary + 1, 1 << shift) >> shift > > = ALIGN_MASK(b + 1, (1 << s) - 1) >> s > > = {[b + 1 + (1 << s) - 1] & ~[(1 << s) - 1]} >> s > > = [b + 1 + (1 << s) - 1] >> s > > = [b + (1 << s)] >> s > > = (b >> s) + 1 > > > > So fixing a potential overflow with the safer shortcut. > > > > Reported-by: Stephen Rothwell > > Signed-off-by: Nicolin Chen > > Cc: Christoph Hellwig > > --- > > arch/powerpc/kernel/iommu.c | 11 +++++------ > > 1 file changed, 5 insertions(+), 6 deletions(-) > > Are you asking for acks, or for maintainers to merge the patches > individually? I was expecting that but Christoph just suggested me to squash them into one so he would merge it: https://lkml.org/lkml/2020/9/1/159 Though I feel it'd be nice to get maintainers' acks before merging. > > diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c > > index 9704f3f76e63..c01ccbf8afdd 100644 > > --- a/arch/powerpc/kernel/iommu.c > > +++ b/arch/powerpc/kernel/iommu.c > > @@ -236,15 +236,14 @@ static unsigned long iommu_range_alloc(struct device *dev, > > } > > } > > > > - if (dev) > > - boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1, > > - 1 << tbl->it_page_shift); > > - else > > - boundary_size = ALIGN(1UL << 32, 1 << tbl->it_page_shift); > > /* 4GB boundary for iseries_hv_alloc and iseries_hv_map */ > > + boundary_size = dev ? dma_get_seg_boundary(dev) : U32_MAX; > > Is there any path that passes a NULL dev anymore? > > Both iseries_hv_alloc() and iseries_hv_map() were removed years ago. > See: > 8ee3e0d69623 ("powerpc: Remove the main legacy iSerie platform code") > > > So maybe we should do a lead-up patch that drops the NULL dev support, > which will then make this patch simpler. The next version of this change will follow Christoph's suggestion by having a helper function that takes care of !dev internally. Thanks Nic > > > > + /* Overflow-free shortcut for: ALIGN(b + 1, 1 << s) >> s */ > > + boundary_size = (boundary_size >> tbl->it_page_shift) + 1; > > > > n = iommu_area_alloc(tbl->it_map, limit, start, npages, tbl->it_offset, > > - boundary_size >> tbl->it_page_shift, align_mask); > > + boundary_size, align_mask); > > if (n == -1) { > > if (likely(pass == 0)) { > > /* First try the pool from the start */ > > -- > > 2.17.1