linux-kernel - [PATCH 1/2] dma-direct: Validate DMA mask against canonical DMA addresses

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260120064255.179425-1-aneesh.kumar@kernel.org>
Date: Tue, 20 Jan 2026 12:12:54 +0530
From: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org>
To: linux-kernel@...r.kernel.org,
	iommu@...ts.linux.dev,
	linux-coco@...ts.linux.dev
Cc: Catalin Marinas <catalin.marinas@....com>,
	will@...nel.org,
	robin.murphy@....com,
	suzuki.poulose@....com,
	jgg@...pe.ca,
	steven.price@....com,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	"Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org>
Subject: [PATCH 1/2] dma-direct: Validate DMA mask against canonical DMA addresses

On systems that apply an address encryption tag or mask to DMA addresses,
DMA mask validation must be performed against the canonical DMA address.
Using a non-canonical (e.g. encrypted or unencrypted) DMA address
can incorrectly fail capability checks, since architecture-specific
encryption bits are not part of the device’s actual DMA addressing
capability. For example, arm64 adds PROT_NS_SHARED to unencrypted DMA
addresses.

Fix this by validating device DMA masks against __phys_to_dma(), ensuring
that the architecture encryption mask does not influence the check.

Fixes: b66e2ee7b6c8 ("dma: Introduce generic dma_addr_*crypted helpers")
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@...nel.org>
---
 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 8e04f72baaa3..a5639e9415f5 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -580,12 +580,12 @@ int dma_direct_supported(struct device *dev, u64 mask)
 
 	/*
 	 * This check needs to be against the actual bit mask value, so use
-	 * phys_to_dma_unencrypted() here so that the SME encryption mask isn't
+	 * __phys_to_dma() here so that the arch specific encryption mask isn't
 	 * part of the check.
 	 */
 	if (IS_ENABLED(CONFIG_ZONE_DMA))
 		min_mask = min_t(u64, min_mask, zone_dma_limit);
-	return mask >= phys_to_dma_unencrypted(dev, min_mask);
+	return mask >= __phys_to_dma(dev, min_mask);
 }
 
 static const struct bus_dma_region *dma_find_range(struct device *dev,
-- 
2.43.0