[PATCH V10 06/12] of: device: Fix overflow of coherent_dma_mask
From: Frank Rowand <hidden>
Date: 2017-04-06 07:01:42
Also in:
linux-acpi, linux-arch, linux-arm-msm, linux-devicetree, linux-iommu, linux-pci, lkml
On 04/04/17 03:18, Sricharan R wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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