[PATCH] iommu: fix integer truncation

[PATCH] iommu: fix integer truncation

[Arnd Bergmann]

On 32-bit architectures, phys_addr_t may be different from dma_add_t,
both smaller and bigger. This can lead to an overflow during an assignment
that clang warns about:

drivers/iommu/dma-iommu.c:230:10: error: implicit conversion from 'dma_addr_t' (aka 'unsigned long long') to
      'phys_addr_t' (aka 'unsigned int') changes value from 18446744073709551615 to 4294967295 [-Werror,-Wconstant-conversion]

Use phys_addr_t here because that is the type that the variable was
declared as.

Fixes: aadad097cd46 ("iommu/dma: Reserve IOVA for PCIe inaccessible DMA address")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/iommu/dma-iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index cc0613c83d71..a9f13313a22f 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -226,8 +226,8 @@ static int iova_reserve_pci_windows(struct pci_dev *dev,
 		start = window->res->end - window->offset + 1;
 		/* If window is last entry */
 		if (window->node.next == &bridge->dma_ranges &&
-		    end != ~(dma_addr_t)0) {
-			end = ~(dma_addr_t)0;
+		    end != ~(phys_addr_t)0) {
+			end = ~(phys_addr_t)0;
 			goto resv_iova;
 		}
 	}
-- 
2.20.0

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Re: [PATCH] iommu: fix integer truncation

[Joerg Roedel]

On Mon, Jun 17, 2019 at 03:30:54PM +0200, Arnd Bergmann wrote:
> On 32-bit architectures, phys_addr_t may be different from dma_add_t,
> both smaller and bigger. This can lead to an overflow during an assignment
> that clang warns about:
> 
> drivers/iommu/dma-iommu.c:230:10: error: implicit conversion from 'dma_addr_t' (aka 'unsigned long long') to
>       'phys_addr_t' (aka 'unsigned int') changes value from 18446744073709551615 to 4294967295 [-Werror,-Wconstant-conversion]
> 
> Use phys_addr_t here because that is the type that the variable was
> declared as.
> 
> Fixes: aadad097cd46 ("iommu/dma: Reserve IOVA for PCIe inaccessible DMA address")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Applied, thanks.
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