From: Kishon Vijay Abraham I Date: Mon, 6 Apr 2020 05:28:36 +0000 (+0530) Subject: dma-direct: fix data truncation in dma_direct_get_required_mask() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=cdcda0d1f8f4ab84efe7cd9921c98364398aefd7;p=linux.git 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 Signed-off-by: Christoph Hellwig --- diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index a8560052a915f..8f4bbdaf965eb 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -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; }