From mboxrd@z Thu Jan 1 00:00:00 1970 From: Frank Rowand Subject: Re: [PATCH V10 06/12] of: device: Fix overflow of coherent_dma_mask Date: Thu, 6 Apr 2017 00:01:11 -0700 Message-ID: <58E5E7B7.1050400@gmail.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1491301105-5274-7-git-send-email-sricharan@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org To: Sricharan R , 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 List-Id: devicetree@vger.kernel.org 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. I agree that the proper solution involves passing a mask instead of a size to arch_setup_dma_ops(). -Frank