Messages in this thread Patch in this message | | | From | Will Deacon <> | Subject | [PATCH v4 2/5] swiotlb: Enforce page alignment in swiotlb_alloc() | Date | Wed, 21 Feb 2024 11:35:01 +0000 |
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When allocating pages from a restricted DMA pool in swiotlb_alloc(), the buffer address is blindly converted to a 'struct page *' that is returned to the caller. In the unlikely event of an allocation bug, page-unaligned addresses are not detected and slots can silently be double-allocated.
Add a simple check of the buffer alignment in swiotlb_alloc() to make debugging a little easier if something has gone wonky.
Cc: Christoph Hellwig <hch@lst.de> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Dexuan Cui <decui@microsoft.com> Reviewed-by: Petr Tesarik <petr.tesarik1@huawei-partners.com> Signed-off-by: Will Deacon <will@kernel.org> --- kernel/dma/swiotlb.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 2ec2cc81f1a2..ab7fbb40bc55 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -1643,6 +1643,12 @@ struct page *swiotlb_alloc(struct device *dev, size_t size) return NULL; tlb_addr = slot_addr(pool->start, index); + if (unlikely(!PAGE_ALIGNED(tlb_addr))) { + dev_WARN_ONCE(dev, 1, "Cannot allocate pages from non page-aligned swiotlb addr 0x%pa.\n", + &tlb_addr); + swiotlb_release_slots(dev, tlb_addr); + return NULL; + } return pfn_to_page(PFN_DOWN(tlb_addr)); } -- 2.44.0.rc0.258.g7320e95886-goog
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