Commit b9826a49 authored Apr 18, 2018 by Jacopo Mondi Committed by Rich Felker May 05, 2018

sh: mm: Fix unprotected access to struct device



With commit ce883130 ("arch/sh: make the DMA mapping
operations observe dev->dma_pfn_offset") the generic DMA allocation
function on which the SH 'dma_alloc_coherent()' function relies on,
accesses the 'dma_pfn_offset' field of struct device.

Unfortunately the 'dma_generic_alloc_coherent()' function is called from
several places with a NULL struct device argument, halting the CPU
during the boot process.

This patch fixes the issue by protecting access to dev->dma_pfn_offset,
with a trivial check for validity. It also passes a valid 'struct device'
in the 'platform_resource_setup_memory()' function which is the main user
of 'dma_alloc_coherent()', and inserts a WARN_ON() check to remind to future
(and existing) bogus users of this function to provide a valid 'struct device'
whenever possible.

Fixes: ce883130 ("arch/sh: make the DMA mapping operations observe dev->dma_pfn_offset")
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Rich Felker <dalias@libc.org>

parent 6cb46597

arch/sh/mm/consistent.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -59,7 +59,9 @@ void dma_generic_alloc_coherent(struct device dev, size_t size,

		split_page(pfn_to_page(virt_to_phys(ret) >> PAGE_SHIFT), order);

		*dma_handle = virt_to_phys(ret) - PFN_PHYS(dev->dma_pfn_offset);
		*dma_handle = virt_to_phys(ret);
		if (!WARN_ON(!dev))
		*dma_handle -= PFN_PHYS(dev->dma_pfn_offset);

		return ret_nocache;
		}
		@@ -69,9 +71,12 @@ void dma_generic_free_coherent(struct device *dev, size_t size,
		unsigned long attrs)
		{
		int order = get_order(size);
		unsigned long pfn = (dma_handle >> PAGE_SHIFT) + dev->dma_pfn_offset;
		unsigned long pfn = dma_handle >> PAGE_SHIFT;
		int k;

		if (!WARN_ON(!dev))
		pfn += dev->dma_pfn_offset;

		for (k = 0; k < (1 << order); k++)
		__free_pages(pfn_to_page(pfn + k), 0);

		@@ -143,7 +148,7 @@ int __init platform_resource_setup_memory(struct platform_device *pdev,
		if (!memsize)
		return 0;

		buf = dma_alloc_coherent(NULL, memsize, &dma_handle, GFP_KERNEL);
		buf = dma_alloc_coherent(&pdev->dev, memsize, &dma_handle, GFP_KERNEL);
		if (!buf) {
		pr_warning("%s: unable to allocate memory\n", name);
		return -ENOMEM;

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