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CVE-2026-98002
iommu/amd: Fix ineffective error check in nested domain allocation
Published 2026-09-25 (24 days ago) by the Linux kernel CNA. Subsystem drivers/iommu. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-98002 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | not affected | 6.12.113-1 | Nothing to do. trixie never shipped the vulnerable code. |
| Debian 14forky | fixed | 7.2.7-1 | Update the kernel and reboot. Fixed in 7.2.7-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.7-1 | Update the kernel and reboot. Fixed in 7.2.7-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
amd_iommu_pdom_id_alloc() returns an int: a domain ID on success, or the negative errno from ida_alloc_range() when the ID space is exhausted or memory is short. amd_iommu_alloc_domain_nested() stores that return value in gdom_info->hdom_id, which is a u32, and only then tests it: gdom_info->hdom_id = amd_iommu_pdom_id_alloc(); if (gdom_info->hdom_id <= 0) { The assignment discards the sign, so -ENOSPC becomes 0xffffffe4 and the test never fires. The nested domain is then set up with a host domain ID that was never allocated, instead of the allocation failing with -ENOSPC. Keep the value in an int, test it there, and store it only once it is known to be valid, which is what the other amd_iommu_pdom_id_alloc() callers already do.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/iommu/amd/nested.c
- What this is
- AMD IOMMU (AMD-VI)MAINTAINERS section matched on drivers/iommu/amd/ · iommu@lists.linux.dev · Maintained
Check it on the machine
grep -wE 'CONFIG_AMD_IOMMU|CONFIG_AMD_IOMMU_IOMMUFD' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian does not build this code in 2 releases. The build rule could not be established for 2 releases, so nothing is claimed about those.
- bookworm, trixie?
- forky, sidn
- ?
- not established - no Makefile entry for the affected file
- n
- not enabled on any flavour - this release does not build the code
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switches
- CONFIG_AMD_IOMMU, CONFIG_AMD_IOMMU_IOMMUFD
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-25 (24 days ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.11%, higher than 1.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/iommu
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 7.0 | 7.2.7 | 80c231f55772 |
| 7.0 | 7.3 | fa5c0827f0b7 |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The patched function amd_iommu_alloc_domain_nested() is reached only via the IOMMU_HWPT_ALLOC ioctl on a local iommufd fd (/dev/iommu) against an AMD vIOMMU (iommufd_hwpt_alloc -> viommu->ops->alloc_domain_nested); no remote protocol carries the input.
- AC:HAttack complexity, high
- The failure path needs ida_alloc_range() in amd_iommu_pdom_id_alloc() to fail: either all 65535 global host domain IDs are in use with a victim domain holding 0xffe4, which lowest-first allocation doesn't let the attacker arrange on demand, or a GFP_ATOMIC failure the attacker cannot force.
- PR:LPrivileges required, low
- Needs a VMM-style user that has been given /dev/iommu (0660) and a bound VFIO device cdev to create a vIOMMU and nested HWPTs; that is delegated device access, not full init-namespace root.
- UI:NUser interaction, none
- The attacker allocates the nested HWPTs and attaches the device themselves; nobody else has to do anything.
- S:CScope, changed
- The unallocated hdom_id (truncated to 0xffe4/0xfff4 by DTE_DOMID_MASK) is written into the DTE by set_dte_nested(), so the nested device shares IOTLB tags with another IOMMU domain, breaking the DMA isolation boundary between domains.
- C:HConfidentiality impact, high
- Because the DomID is aliased, the device's DMA can hit IOTLB translations cached for the other domain and read memory belonging to that domain.
- I:HIntegrity impact, high
- The same aliased IOTLB entries let the device's DMA writes land in the other domain's pages, corrupting memory outside the nested domain.
- A:HAvailability impact, high
- Stray DMA writes into another domain's memory, plus invalidations for the parent S2 hitting the shared hdom_id, can corrupt host or guest memory used by other devices and bring them down.