mm: fix overflow in vm_map_ram() (65ee03c4) · Commits · 戴 / test

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>

mm/vmalloc.c

+5 −4

Original line number	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)
		{
		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;

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