Commit 1a3389ff authored by Catalin Marinas's avatar Catalin Marinas Committed by Greg Kroah-Hartman
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drivers: dma-mapping: Do not leave an invalid area->pages pointer in dma_common_contiguous_remap() 



The dma_common_pages_remap() function allocates a vm_struct object and
initialises the pages pointer to value passed as argument. However, when
this function is called dma_common_contiguous_remap(), the pages array
is only temporarily allocated, being freed shortly after
dma_common_contiguous_remap() returns. Architecture code checking the
validity of an area->pages pointer would incorrectly dereference already
freed pointers. This has been exposed by the arm64 commit 44176bb3
("arm64: Add support for DMA_ATTR_FORCE_CONTIGUOUS to IOMMU").

Fixes: 513510dd ("common: dma-mapping: introduce common remapping functions")
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reported-by: default avatarAndrzej Hajda <a.hajda@samsung.com>
Acked-by: default avatarLaura Abbott <labbott@redhat.com>
Reviewed-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e622ec57

drivers/base/dma-mapping.c

+24 −9
Original line number Diff line number Diff line
@@ -275,6 +275,24 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma, 
EXPORT_SYMBOL(dma_common_mmap);



#ifdef CONFIG_MMU

static struct vm_struct *__dma_common_pages_remap(struct page **pages,

			size_t size, unsigned long vm_flags, pgprot_t prot,

			const void *caller)

{

	struct vm_struct *area;



	area = get_vm_area_caller(size, vm_flags, caller);

	if (!area)

		return NULL;



	if (map_vm_area(area, prot, pages)) {

		vunmap(area->addr);

		return NULL;

	}



	return area;

}



/*

 * remaps an array of PAGE_SIZE pages into another vm_area

 * Cannot be used in non-sleeping contexts
@@ -285,17 +303,12 @@ void *dma_common_pages_remap(struct page **pages, size_t size, 
{

	struct vm_struct *area;



	area = get_vm_area_caller(size, vm_flags, caller);

	area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);

	if (!area)

		return NULL;



	area->pages = pages;



	if (map_vm_area(area, prot, pages)) {

		vunmap(area->addr);

		return NULL;

	}



	return area->addr;

}
@@ -310,7 +323,7 @@ void *dma_common_contiguous_remap(struct page *page, size_t size, 
{

	int i;

	struct page **pages;

	void *ptr;

	struct vm_struct *area;



	pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);

	if (!pages)
@@ -319,11 +332,13 @@ void *dma_common_contiguous_remap(struct page *page, size_t size, 
	for (i = 0; i < (size >> PAGE_SHIFT); i++)

		pages[i] = nth_page(page, i);



	ptr = dma_common_pages_remap(pages, size, vm_flags, prot, caller);

	area = __dma_common_pages_remap(pages, size, vm_flags, prot, caller);



	kfree(pages);



	return ptr;

	if (!area)

		return NULL;

	return area->addr;

}



/*

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