Messages in this thread Patch in this message | | | From | Lu Baolu <> | Subject | [PATCH v5 06/10] swiotlb: Zero out bounce buffer for untrusted device | Date | Thu, 25 Jul 2019 11:17:13 +0800 |
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This is necessary to avoid exposing valid kernel data to any malicious device.
Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> --- kernel/dma/swiotlb.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 43c88626a1f3..edc84a00b9f9 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -35,6 +35,7 @@ #include <linux/scatterlist.h> #include <linux/mem_encrypt.h> #include <linux/set_memory.h> +#include <linux/pci.h> #ifdef CONFIG_DEBUG_FS #include <linux/debugfs.h> #endif @@ -562,6 +563,11 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, */ for (i = 0; i < nslots; i++) io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT); + + /* Zero out the bounce buffer if the consumer is untrusted. */ + if (dev_is_untrusted(hwdev)) + memset(phys_to_virt(tlb_addr), 0, alloc_size); + if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)) swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE); -- 2.17.1
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