linux-kernel - [PATCH v3] iommu/riscv: prevent NULL deref in iova_to

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Message-Id: <20250815071244.13982-1-huangxianliang@lanxincomputing.com>
Date: Fri, 15 Aug 2025 15:12:44 +0800
From: "XianLiang Huang" <huangxianliang@...xincomputing.com>
To: <tjeznach@...osinc.com>
Cc: <markus.elfring@....de>, <joro@...tes.org>, <will@...nel.org>, 
	<robin.murphy@....com>, <paul.walmsley@...ive.com>, <palmer@...belt.com>, 
	<aou@...s.berkeley.edu>, <alex@...ti.fr>, <iommu@...ts.linux.dev>, 
	<linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>, 
	<huangxianliang@...xincomputing.com>
Subject: [PATCH v3] iommu/riscv: prevent NULL deref in iova_to_phys

The riscv_iommu_pte_fetch() function returns either NULL for
unmapped/never-mapped iova, or a valid leaf pte pointer that requires no
further validation.

riscv_iommu_iova_to_phys() failed to handle NULL returns. Fix by adding NULL
check before dereferencing and returning 0 for invalid iova.

Fixes: 488ffbf18171 ("iommu/riscv: Paging domain support")
Cc: Tomasz Jeznach <tjeznach@...osinc.com>
Signed-off-by: XianLiang Huang <huangxianliang@...xincomputing.com>
---
Changes
v3:
- Remove redundant pte validation in riscv_iommu_iova_to_phys
- Improve subject line to emphasize prevention

v2:
- Refine problem description
- Add "Fixes" tag
---
 drivers/iommu/riscv/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index 2d0d31ba2886..0eae2f4bdc5e 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -1283,7 +1283,7 @@ static phys_addr_t riscv_iommu_iova_to_phys(struct iommu_domain *iommu_domain,
 	unsigned long *ptr;
 
 	ptr = riscv_iommu_pte_fetch(domain, iova, &pte_size);
-	if (_io_pte_none(*ptr) || !_io_pte_present(*ptr))
+	if (!ptr)
 		return 0;
 
 	return pfn_to_phys(__page_val_to_pfn(*ptr)) | (iova & (pte_size - 1));
-- 
2.34.1