Subject: [PATCH 26/34] dma-direct: add dma address sanity checks

From: Christoph Hellwig <[email-masked]>
Date: Fri, 12 Jan 2018 09:42:24 +0100

Roughly based on the x86 pci-nommu implementation.

Signed-off-by: Christoph Hellwig <[email-masked]>
---
 lib/dma-direct.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/lib/dma-direct.c b/lib/dma-direct.c
index 12ea9653781b..32fd4d9e4c47 100644
--- a/lib/dma-direct.c
+++ b/lib/dma-direct.c
@@ -9,6 +9,23 @@
 #include <linux/scatterlist.h>
 #include <linux/pfn.h>
 
+#define DIRECT_MAPPING_ERROR		0
+
+static bool
+check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
+		const char *caller)
+{
+	if (unlikely(dev && !dma_capable(dev, dma_addr, size))) {
+		if (*dev->dma_mask >= DMA_BIT_MASK(32)) {
+			dev_err(dev,
+				"%s: overflow %pad+%zu of device mask %llx\n",
+				caller, &dma_addr, size, *dev->dma_mask);
+		}
+		return false;
+	}
+	return true;
+}
+
 static void *dma_direct_alloc(struct device *dev, size_t size,
 		dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
 {
@@ -31,7 +48,11 @@ static dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
 		unsigned long offset, size_t size, enum dma_data_direction dir,
 		unsigned long attrs)
 {
-	return phys_to_dma(dev, page_to_phys(page)) + offset;
+	dma_addr_t dma_addr = phys_to_dma(dev, page_to_phys(page)) + offset;
+
+	if (!check_addr(dev, dma_addr, size, __func__))
+		return DIRECT_MAPPING_ERROR;
+	return dma_addr;
 }
 
 static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
@@ -44,16 +65,24 @@ static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
 		BUG_ON(!sg_page(sg));
 
 		sg_dma_address(sg) = phys_to_dma(dev, sg_phys(sg));
+		if (!check_addr(dev, sg_dma_address(sg), sg->length, __func__))
+			return 0;
 		sg_dma_len(sg) = sg->length;
 	}
 
 	return nents;
 }
 
+static int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+	return dma_addr == DIRECT_MAPPING_ERROR;
+}
+
 const struct dma_map_ops dma_direct_ops = {
 	.alloc			= dma_direct_alloc,
 	.free			= dma_direct_free,
 	.map_page		= dma_direct_map_page,
 	.map_sg			= dma_direct_map_sg,
+	.mapping_error		= dma_direct_mapping_error,
 };
 EXPORT_SYMBOL(dma_direct_ops);
-- 
2.14.2