Commit 34fe6537 authored Dec 14, 2020 by Andrew Morton Committed by Linus Torvalds Dec 15, 2020

mm/vmalloc.c:__vmalloc_area_node(): avoid 32-bit overflow

With a machine with 3 TB (more than 2 TB memory).  If you use vmalloc to
allocate > 2 TB memory, the array_size below will be overflowed.

The array_size is an unsigned int and can only be used to allocate less
than 2 TB memory.  If you pass 2*1028*1028*1024*1024 = 2 * 2^40 in the
argument of vmalloc.  The array_size will become 2*2^31 = 2^32.  The 2^32
cannot be store with a 32 bit integer.

The fix is to change the type of array_size to unsigned long.

[akpm@linux-foundation.org: rework for current mainline]

Link: https://bugzilla.kernel.org/show_bug.cgi?id=210023


Reported-by:  <hsinhuiwu@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent d5037d1d

mm/vmalloc.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -2461,9 +2461,11 @@ static void __vmalloc_area_node(struct vm_struct area, gfp_t gfp_mask,
		{
		const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) \| __GFP_ZERO;
		unsigned int nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
		unsigned int array_size = nr_pages * sizeof(struct page *), i;
		unsigned long array_size;
		unsigned int i;
		struct page **pages;

		array_size = (unsigned long)nr_pages * sizeof(struct page *);
		gfp_mask \|= __GFP_NOWARN;
		if (!(gfp_mask & (GFP_DMA \| GFP_DMA32)))
		gfp_mask \|= __GFP_HIGHMEM;

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