From 4a54d16f615f41489b2ecbc940f6eb2618ddafd6 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 29 Apr 2019 09:16:42 -0500 Subject: dma-mapping: truncate dma masks to what dma_addr_t can hold The dma masks in struct device are always 64-bits wide. But for builds using a 32-bit dma_addr_t we need to ensure we don't store an unsupportable value. Before Linux 5.0 this was handled at least by the ARM dma mapping code by never allowing to set a larger dma_mask, but these days we allow the driver to just set the largest supported value and never fall back to a smaller one. Ensure this always works by truncating the value. Fixes: 9eb9e96e97b3 ("Documentation/DMA-API-HOWTO: update dma_mask sections") Signed-off-by: Christoph Hellwig --- kernel/dma/mapping.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index f7afdadb6770..1f628e7ac709 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -317,6 +317,12 @@ void arch_dma_set_mask(struct device *dev, u64 mask); int dma_set_mask(struct device *dev, u64 mask) { + /* + * Truncate the mask to the actually supported dma_addr_t width to + * avoid generating unsupportable addresses. + */ + mask = (dma_addr_t)mask; + if (!dev->dma_mask || !dma_supported(dev, mask)) return -EIO; @@ -330,6 +336,12 @@ EXPORT_SYMBOL(dma_set_mask); #ifndef CONFIG_ARCH_HAS_DMA_SET_COHERENT_MASK int dma_set_coherent_mask(struct device *dev, u64 mask) { + /* + * Truncate the mask to the actually supported dma_addr_t width to + * avoid generating unsupportable addresses. + */ + mask = (dma_addr_t)mask; + if (!dma_supported(dev, mask)) return -EIO; -- cgit v1.2.3