iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs

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Summary

CVECVE-2026-64186
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 16:18:01 UTC
Updated2026-07-19 16:18:01 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs In iommu_mmio_write() and iommu_capability_write(), the variables dbg_mmio_offset and dbg_cap_offset are declared as int. However, they are populated using kstrtou32_from_user(). If a user provides a sufficiently large value, it can become a negative integer. Prior to this patch, the AMD IOMMU debugfs implementation was already protected by different mechanisms. 1. #define OFS_IN_SZ 8 ensures the user string <= 8 bytes, so e.g. 0xffffffff isn't a valid input. if (cnt > OFS_IN_SZ) return -EINVAL; 2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int and iommu->mmio_phys_end is u64 if (dbg_mmio_offset > iommu->mmio_phys_end - sizeof(u64)) return -EINVAL; 3. The show handlers would currently catch the negative number and refuse to perform the read. Replace kstrtou32_from_user() with kstrtos32_from_user() to parse the input, and check for negative values to explicitly prevent out-of-bounds memory accesses directly in iommu_mmio_write() and iommu_capability_write().

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 7a4ee419e8c144b747a8915856e91a034d7c8f34 488d2c76bd9f78433a70690d1054bfae3d39a407 git Not specified
CNA Linux Linux affected 7a4ee419e8c144b747a8915856e91a034d7c8f34 62f9dfbf1aceae88b03c5ca08f7d36e943939dec git Not specified
CNA Linux Linux affected 7a4ee419e8c144b747a8915856e91a034d7c8f34 8dfd3d8d74435344ee8dc9237596959c8b2a6cbe git Not specified
CNA Linux Linux affected 6.17 Not specified
CNA Linux Linux unaffected 6.17 semver Not specified
CNA Linux Linux unaffected 6.18.34 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.11 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/488d2c76bd9f78433a70690d1054bfae3d39a407 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8dfd3d8d74435344ee8dc9237596959c8b2a6cbe 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/62f9dfbf1aceae88b03c5ca08f7d36e943939dec 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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