Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756703AbdDFLBy (ORCPT ); Thu, 6 Apr 2017 07:01:54 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:44412 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752603AbdDFLBl (ORCPT ); Thu, 6 Apr 2017 07:01:41 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org E1FF6607C1 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=sricharan@codeaurora.org Subject: Re: [PATCH V10 06/12] of: device: Fix overflow of coherent_dma_mask To: Frank Rowand , robin.murphy@arm.com, will.deacon@arm.com, joro@8bytes.org, lorenzo.pieralisi@arm.com, iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org, m.szyprowski@samsung.com, bhelgaas@google.com, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, tn@semihalf.com, hanjun.guo@linaro.org, okaya@codeaurora.org, robh+dt@kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, sudeep.holla@arm.com, rjw@rjwysocki.net, lenb@kernel.org, catalin.marinas@arm.com, arnd@arndb.de, linux-arch@vger.kernel.org, gregkh@linuxfoundation.org References: <1489086061-9356-1-git-send-email-sricharan@codeaurora.org> <1491301105-5274-1-git-send-email-sricharan@codeaurora.org> <1491301105-5274-7-git-send-email-sricharan@codeaurora.org> <58E5E7B7.1050400@gmail.com> From: Sricharan R Message-ID: Date: Thu, 6 Apr 2017 16:31:30 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <58E5E7B7.1050400@gmail.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2483 Lines: 63 Hi Frank, On 4/6/2017 12:31 PM, Frank Rowand wrote: > On 04/04/17 03:18, Sricharan R wrote: >> Size of the dma-range is calculated as coherent_dma_mask + 1 >> and passed to arch_setup_dma_ops further. It overflows when >> the coherent_dma_mask is set for full 64 bits 0xFFFFFFFFFFFFFFFF, >> resulting in size getting passed as 0 wrongly. Fix this by >> passsing in max(mask, mask + 1). Note that in this case >> when the mask is set to full 64bits, we will be passing the mask >> itself to arch_setup_dma_ops instead of the size. The real fix >> for this should be to make arch_setup_dma_ops receive the >> mask and handle it, to be done in the future. >> >> Signed-off-by: Sricharan R >> --- >> drivers/of/device.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/of/device.c b/drivers/of/device.c >> index c17c19d..c2ae6bb 100644 >> --- a/drivers/of/device.c >> +++ b/drivers/of/device.c >> @@ -107,7 +107,7 @@ void of_dma_configure(struct device *dev, struct device_node *np) >> ret = of_dma_get_range(np, &dma_addr, &paddr, &size); >> if (ret < 0) { >> dma_addr = offset = 0; >> - size = dev->coherent_dma_mask + 1; >> + size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1); >> } else { >> offset = PFN_DOWN(paddr - dma_addr); >> dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset); >> > > NACK. > > Passing an invalid size to arch_setup_dma_ops() is only part of the problem. > size is also used in of_dma_configure() before calling arch_setup_dma_ops(): > > dev->coherent_dma_mask = min(dev->coherent_dma_mask, > DMA_BIT_MASK(ilog2(dma_addr + size))); > *dev->dma_mask = min((*dev->dma_mask), > DMA_BIT_MASK(ilog2(dma_addr + size))); > > which would be incorrect for size == 0xffffffffffffffffULL when > dma_addr != 0. So the proposed fix really is not papering over > the base problem very well. > Ok, but with your fix for of_dma_get_range and the above fix, dma_addr will be '0' when size = 0xffffffffffffffffULL, but DMA_BIT_MASK(ilog2(dma_addr + size)) would be wrong though, making coherent_dma_mask to be smaller 0x7fffffffffffffffULL. Regards, Sricharan > I agree that the proper solution involves passing a mask instead > of a size to arch_setup_dma_ops(). > -- "QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation