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Commit 65ee03c4 authored by Guillermo Julián Moreno's avatar Guillermo Julián Moreno Committed by Linus Torvalds
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mm: fix overflow in vm_map_ram() 

When remapping pages accounting for 4G or more memory space, the
operation 'count << PAGE_SHIFT' overflows as it is performed on an
integer.  Solution: cast before doing the bitshift.

[akpm@linux-foundation.org: fix vm_unmap_ram() also]
[akpm@linux-foundation.org: fix vmap() as well, per Guillermo]
Link: http://lkml.kernel.org/r/etPan.57175fb3.7a271c6b.2bd@naudit.es


Signed-off-by: default avatarGuillermo Julián Moreno <guillermo.julian@naudit.es>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4340fa55

mm/vmalloc.c

+5 −4
Original line number Original line Diff line number Diff line
@@ -1105,7 +1105,7 @@ EXPORT_SYMBOL_GPL(vm_unmap_aliases); 
 */

 */

void vm_unmap_ram(const void *mem, unsigned int count)

void vm_unmap_ram(const void *mem, unsigned int count)

{

{

	unsigned long size = count << PAGE_SHIFT;

	unsigned long size = (unsigned long)count << PAGE_SHIFT;

	unsigned long addr = (unsigned long)mem;

	unsigned long addr = (unsigned long)mem;





	BUG_ON(!addr);

	BUG_ON(!addr);
@@ -1140,7 +1140,7 @@ EXPORT_SYMBOL(vm_unmap_ram); 
 */

 */

void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)

void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)

{

{

	unsigned long size = count << PAGE_SHIFT;

	unsigned long size = (unsigned long)count << PAGE_SHIFT;

	unsigned long addr;

	unsigned long addr;

	void *mem;

	void *mem;
@@ -1574,14 +1574,15 @@ void *vmap(struct page **pages, unsigned int count, 
		unsigned long flags, pgprot_t prot)

		unsigned long flags, pgprot_t prot)

{

{

	struct vm_struct *area;

	struct vm_struct *area;

	unsigned long size;		/* In bytes */





	might_sleep();

	might_sleep();





	if (count > totalram_pages)

	if (count > totalram_pages)

		return NULL;

		return NULL;





	area = get_vm_area_caller((count << PAGE_SHIFT), flags,

	size = (unsigned long)count << PAGE_SHIFT;

					__builtin_return_address(0));

	area = get_vm_area_caller(size, flags, __builtin_return_address(0));

	if (!area)

	if (!area)

		return NULL;

		return NULL;