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=-9.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 4094BC433E6 for ; Tue, 1 Sep 2020 13:30:17 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 AAAB6206EB for ; Tue, 1 Sep 2020 13:30:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="pXwfFcp7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AAAB6206EB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4Bgnxf0ZfyzDqT4 for ; Tue, 1 Sep 2020 23:30:14 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4Bgntp71CwzDqJ2 for ; Tue, 1 Sep 2020 23:27:46 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=pXwfFcp7; dkim-atps=neutral Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4Bgntf72DLz9sTN; Tue, 1 Sep 2020 23:27:38 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1598966866; bh=b8fBMPirmgEDaVPbjXdRIYPwIrTUtQaTXRmfGBF/egk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=pXwfFcp7DEZhdSaVT5PD8DrmDNJcZnA4u3LePXbs+Xb49cAmRXaxJrmXg/VJlWIzR Q9Z+EfZBm7r6mhEVXxyXQhUmW0fa5OWGfrmOVAZI3itGQAU61ebluXbCJK+AIc60vF 1lpEQtozskWFVBMd7eJLB6Kr3ed2+dixG5IYLvugFo8ywj0S6XpgkfnAthm3BhrzXv 8D0og0Lq9pFYRuwgHyCnfhfBZXrYFBGSojjeGeHhiOdKVVtQpLLH9UWs9qF4OuV5Cr KzxdsR4L7qCBMFnd1HxBtLQKZU2Du8AyMTHI6pRxfwvNsOSSUSd9mxXbEuet6K+c7h OfGS3/kjMeThw== From: Michael Ellerman To: Nicolin Chen , 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 Subject: Re: [RESEND][PATCH 1/7] powerpc/iommu: Avoid overflow at boundary_size In-Reply-To: <20200831203811.8494-2-nicoleotsuka@gmail.com> References: <20200831203811.8494-1-nicoleotsuka@gmail.com> <20200831203811.8494-2-nicoleotsuka@gmail.com> Date: Tue, 01 Sep 2020 23:27:36 +1000 Message-ID: <87lfht1vav.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sfr@canb.auug.org.au, linux-ia64@vger.kernel.org, linux-parisc@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, hch@lst.de Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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? > 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. cheers > + /* 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