Commit cdcda0d1 authored Apr 06, 2020 by Kishon Vijay Abraham I Committed by Christoph Hellwig Apr 08, 2020

dma-direct: fix data truncation in dma_direct_get_required_mask()



The upper 32-bit physical address gets truncated inadvertently
when dma_direct_get_required_mask() invokes phys_to_dma_direct().
This results in dma_addressing_limited() return incorrect value
when used in platforms with LPAE enabled.
Fix it here by explicitly type casting 'max_pfn' to phys_addr_t
in order to prevent overflow of intermediate value while evaluating
'(max_pfn - 1) << PAGE_SHIFT'.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

parent f5e94d10

kernel/dma/direct.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -39,7 +39,8 @@ static inline struct page dma_direct_to_page(struct device dev,

		u64 dma_direct_get_required_mask(struct device *dev)
		{
		u64 max_dma = phys_to_dma_direct(dev, (max_pfn - 1) << PAGE_SHIFT);
		phys_addr_t phys = (phys_addr_t)(max_pfn - 1) << PAGE_SHIFT;
		u64 max_dma = phys_to_dma_direct(dev, phys);

		return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
		}

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