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mm: fix overflow in vm_map_ram()

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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: Guillermo Julián Moreno <guillermo.julian@naudit.es>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Guillermo Julián Moreno 2016-06-03 14:55:33 -07:00 committed by Linus Torvalds
parent 4340fa5529
commit 65ee03c4b9
1 changed files with 5 additions and 4 deletions
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9
mm/vmalloc.c
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@ -1105,7 +1105,7 @@ EXPORT_SYMBOL_GPL(vm_unmap_aliases);
*/
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;
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)
{
unsigned long size = count << PAGE_SHIFT;
unsigned long size = (unsigned long)count << PAGE_SHIFT;
unsigned long addr;
void *mem;
@ -1574,14 +1574,15 @@ void *vmap(struct page **pages, unsigned int count,
unsigned long flags, pgprot_t prot)
{
struct vm_struct *area;
unsigned long size; /* In bytes */
might_sleep();
if (count > totalram_pages)
return NULL;
area = get_vm_area_caller((count << PAGE_SHIFT), flags,
__builtin_return_address(0));
size = (unsigned long)count << PAGE_SHIFT;
area = get_vm_area_caller(size, flags, __builtin_return_address(0));
if (!area)
return NULL;