linux-kernel - [PATCH v3 1/2] dma-mapping: Add vmap checks to dma_map

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Date:   Thu, 10 Oct 2019 15:28:28 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Christoph Hellwig <hch@....de>
Cc:     Kees Cook <keescook@...omium.org>,
        Robin Murphy <robin.murphy@....com>,
        Laura Abbott <labbott@...hat.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Allison Randal <allison@...utok.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <swboyd@...omium.org>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Semmle Security Reports <security-reports@...mle.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/2] dma-mapping: Add vmap checks to dma_map_single()

As we've seen from USB and other areas[1], we need to always do runtime
checks for DMA operating on memory regions that might be remapped. This
adds vmap checks (similar to those already in USB but missing in other
places) into dma_map_single() so all callers benefit from the checking.

[1] https://git.kernel.org/linus/3840c5b78803b2b6cc1ff820100a74a092c40cbb

Suggested-by: Laura Abbott <labbott@...hat.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 include/linux/dma-mapping.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 4a1c4fca475a..ff4e91c66f44 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -583,6 +583,12 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
 static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
 		size_t size, enum dma_data_direction dir, unsigned long attrs)
 {
+	/* DMA must never operate on areas that might be remapped. */
+	if (unlikely(is_vmalloc_addr(ptr))) {
+		dev_warn_once(dev, "bad map: %zu bytes in vmalloc\n", size);
+		return DMA_MAPPING_ERROR;
+	}
+
 	debug_dma_map_single(dev, ptr, size);
 	return dma_map_page_attrs(dev, virt_to_page(ptr), offset_in_page(ptr),
 			size, dir, attrs);
-- 
2.17.1