On 12/11/2013 2:42 AM, Will Deacon wrote:
On Tue, Dec 10, 2013 at 09:43:35PM +0000, Laura Abbott wrote:
The device passed in to dma_alloc may be NULL. Check for this before
trying to get the coherent_dma_mask.
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Signed-off-by: Laura Abbott <lauraa@xxxxxxxxxxxxxx>
---
arch/arm64/mm/dma-mapping.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 4bd7579..4134212 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -33,7 +33,7 @@ static void *arm64_swiotlb_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flags,
struct dma_attrs *attrs)
{
- if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
+ if (dev && IS_ENABLED(CONFIG_ZONE_DMA32) &&
dev->coherent_dma_mask <= DMA_BIT_MASK(32))
flags |= GFP_DMA32;
return swiotlb_alloc_coherent(dev, size, dma_handle, flags);
Unless I'm misreading the code, it looks like there are paths through
swiotlb_alloc_coherent that will dereference the dev parameter without a
NULL check. Are you sure we should allow for NULL devices here?
The current ARM code allows for NULL devices so that would be a
difference in behavior between arm and arm64. We're also relying on this
behavior in some code. Where exactly in swiotlb_alloc_coherent does this
dereference happen? The only one I see is checked with 'if (hwdev &&
hwdev->coherent_dma_mask)'
Will
Thanks,
Laura
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