[PATCH 27/67] dma-direct: add dma address sanity checks

[Christoph Hellwig <hch@lst.de>]

Roughly based on the x86 pci-nommu implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 lib/dma-direct.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/lib/dma-direct.c b/lib/dma-direct.c
index 0e087650e86b..ddd9dcf4e663 100644
--- a/lib/dma-direct.c
+++ b/lib/dma-direct.c
@@ -9,6 +9,24 @@
 #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 %llx+%zu of device mask %llx\n",
+                               caller, (long long)dma_addr, size,
+                               (long long)*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 +49,11 @@ 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,
@@ -44,17 +66,25 @@ 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,
        .is_phys                = true,
 };
 EXPORT_SYMBOL(dma_direct_ops);
-- 
2.14.2