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Commit 51635ad2 authored by Lennert Buytenhek's avatar Lennert Buytenhek Committed by Russell King
Browse files

[ARM] 3813/1: prevent >= 4G /dev/mem mmap() 



Prevent userland from mapping in physical address regions >= 4G by
checking for that in valid_mmap_phys_addr_range().

Unfortunately, we cannot override valid_mmap_phys_addr_range() without
also overriding valid_phys_addr_range(), so copy drivers/char/mem.c's
version of valid_phys_addr_range() over to arch/arm/mm/mmap.c as well.

Signed-off-by: default avatarLennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent bf11d26c

arch/arm/mm/mmap.c

+22 −0
Original line number Diff line number Diff line
@@ -114,3 +114,25 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, 
	}

}





/*

 * You really shouldn't be using read() or write() on /dev/mem.  This

 * might go away in the future.

 */

int valid_phys_addr_range(unsigned long addr, size_t size)

{

	if (addr + size > __pa(high_memory))

		return 0;



	return 1;

}



/*

 * We don't use supersection mappings for mmap() on /dev/mem, which

 * means that we can't map the memory area above the 4G barrier into

 * userspace.

 */

int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)

{

	return !(pfn + (size >> PAGE_SHIFT) > 0x00100000);

}

include/asm-arm/io.h

+4 −0
Original line number Diff line number Diff line
@@ -280,6 +280,10 @@ extern void pci_iounmap(struct pci_dev *dev, void __iomem *addr); 
#define BIOVEC_MERGEABLE(vec1, vec2)	\

	((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))



#define ARCH_HAS_VALID_PHYS_ADDR_RANGE

extern int valid_phys_addr_range(unsigned long addr, size_t size);

extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size);



/*

 * Convert a physical pointer to a virtual kernel pointer for /dev/mem

 * access