Commit cdcda0d1 authored by Kishon Vijay Abraham I's avatar Kishon Vijay Abraham I Committed by Christoph Hellwig
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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: default avatarKishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: default avatarChristoph 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;

}