From 374e7af67d9d9d6103c2cfc8eb32abfecf3a2fd8 Mon Sep 17 00:00:00 2001 From: Chaitanya Kulkarni Date: Fri, 19 Dec 2025 15:28:58 -0800 Subject: [PATCH] iommu/io-pgtable-arm: fix size_t signedness bug in unmap path __arm_lpae_unmap() returns size_t but was returning -ENOENT (negative error code) when encountering an unmapped PTE. Since size_t is unsigned, -ENOENT (typically -2) becomes a huge positive value (0xFFFFFFFFFFFFFFFE on 64-bit systems). This corrupted value propagates through the call chain: __arm_lpae_unmap() returns -ENOENT as size_t -> arm_lpae_unmap_pages() returns it -> __iommu_unmap() adds it to iova address -> iommu_pgsize() triggers BUG_ON due to corrupted iova This can cause IOVA address overflow in __iommu_unmap() loop and trigger BUG_ON in iommu_pgsize() from invalid address alignment. Fix by returning 0 instead of -ENOENT. The WARN_ON already signals the error condition, and returning 0 (meaning "nothing unmapped") is the correct semantic for size_t return type. This matches the behavior of other io-pgtable implementations (io-pgtable-arm-v7s, io-pgtable-dart) which return 0 on error conditions. Fixes: 3318f7b5cefb ("iommu/io-pgtable-arm: Add quirk to quiet WARN_ON()") Cc: stable@vger.kernel.org Signed-off-by: Chaitanya Kulkarni Acked-by: Will Deacon Reviewed-by: Jason Gunthorpe Reviewed-by: Rob Clark Signed-off-by: Joerg Roedel --- drivers/iommu/io-pgtable-arm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index e6626004b323..05d63fe92e43 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -637,7 +637,7 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data, pte = READ_ONCE(*ptep); if (!pte) { WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN)); - return -ENOENT; + return 0; } /* If the size matches this level, we're in the right place */ -- 2.47.3