From cdcda0d1f8f4ab84efe7cd9921c98364398aefd7 Mon Sep 17 00:00:00 2001
From: Kishon Vijay Abraham I <kishon@ti.com>
Date: Mon, 6 Apr 2020 10:58:36 +0530
Subject: [PATCH] dma-direct: fix data truncation in dma_direct_get_required_mask()
Git-commit: cdcda0d1f8f4ab84efe7cd9921c98364398aefd7
Patch-mainline: v5.7-rc1
References: git-fixes

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 kernel/dma/direct.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index a8560052a915..8f4bbdaf965e 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;
 }
-- 
2.16.4