linux-kernel - [PATCH v2] swiotlb: avoid potential left shift overflow

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Message-Id: <20220819084537.52374-1-chao.gao@intel.com>
Date:   Fri, 19 Aug 2022 16:45:37 +0800
From:   Chao Gao <chao.gao@...el.com>
To:     linux-kernel@...r.kernel.org, iommu@...ts.linux.dev
Cc:     hch@...radead.org, m.szyprowski@...sung.com, robin.murphy@....com,
        jxgao@...gle.com, konrad.wilk@...cle.com,
        Chao Gao <chao.gao@...el.com>
Subject: [PATCH v2] swiotlb: avoid potential left shift overflow

The second operand passed to slot_addr() is declared as int or unsigned int
in all call sites. The left-shift to get the offset of a slot can overflow
if swiotlb size is larger than 4G.

Convert the macro to an inline function and declare the second argument as
phys_addr_t to avoid the potential overflow.

Fixes: 26a7e094783d ("swiotlb: refactor swiotlb_tbl_map_single")
Signed-off-by: Chao Gao <chao.gao@...el.com>
---
 kernel/dma/swiotlb.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index c5a9190b218f..41ea9fb3efe1 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -579,7 +579,10 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size
 	}
 }
 
-#define slot_addr(start, idx)	((start) + ((idx) << IO_TLB_SHIFT))
+static inline phys_addr_t slot_addr(phys_addr_t start, phys_addr_t idx)
+{
+	return start + (idx << IO_TLB_SHIFT);
+}
 
 /*
  * Carefully handle integer overflow which can occur when boundary_mask == ~0UL.

base-commit: 5c850d31880e00f063fa2a3746ba212c4bcc510f
-- 
2.25.1