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

Christoph Hellwig
2018-01-12T08:47:05Z

Roughly based on the x86 pci-nommu implementation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
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