From 4a37f3dd9a83186cb88d44808ab35b78375082c9 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Fri, 20 May 2022 18:10:13 +0100 Subject: [PATCH] dma-direct: don't over-decrypt memory The original x86 sev_alloc() only called set_memory_decrypted() on memory returned by alloc_pages_node(), so the page order calculation fell out of that logic. However, the common dma-direct code has several potential allocators, not all of which are guaranteed to round up the underlying allocation to a power-of-two size, so carrying over that calculation for the encryption/decryption size was a mistake. Fix it by rounding to a *number* of pages, rather than an order. Until recently there was an even worse interaction with DMA_DIRECT_REMAP where we could have ended up decrypting part of the next adjacent vmalloc area, only averted by no architecture actually supporting both configs at once. Don't ask how I found that one out... Fixes: c10f07aa27da ("dma/direct: Handle force decryption for DMA coherent buffers in common code") Signed-off-by: Robin Murphy Signed-off-by: Christoph Hellwig Acked-by: David Rientjes --- kernel/dma/direct.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 3e7f4aab740e..e978f36e6be8 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -79,7 +79,7 @@ static int dma_set_decrypted(struct device *dev, void *vaddr, size_t size) { if (!force_dma_unencrypted(dev)) return 0; - return set_memory_decrypted((unsigned long)vaddr, 1 << get_order(size)); + return set_memory_decrypted((unsigned long)vaddr, PFN_UP(size)); } static int dma_set_encrypted(struct device *dev, void *vaddr, size_t size) @@ -88,7 +88,7 @@ static int dma_set_encrypted(struct device *dev, void *vaddr, size_t size) if (!force_dma_unencrypted(dev)) return 0; - ret = set_memory_encrypted((unsigned long)vaddr, 1 << get_order(size)); + ret = set_memory_encrypted((unsigned long)vaddr, PFN_UP(size)); if (ret) pr_warn_ratelimited("leaking DMA memory that can't be re-encrypted\n"); return ret;