Bug 2492422 (CVE-2026-52952)

Summary: CVE-2026-52952 kernel: iommu: Fix WARN_ON in __iommu_group_set_domain_nofail() due to reset
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Input/Output Memory Management Unit (IOMMU) subsystem, which manages how devices access system memory. A race condition, a situation where multiple operations occur in an unpredictable order, exists during device recovery when multiple memory domains are being attached concurrently. This can lead to a Use-After-Free (UAF) vulnerability, where the system attempts to use memory that has already been released, potentially allowing a local attacker to execute unauthorized code or cause the system to crash (denial of service).
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Description OSIDB Bzimport 2026-06-24 18:11:20 UTC 
In the Linux kernel, the following vulnerability has been resolved:

iommu: Fix WARN_ON in __iommu_group_set_domain_nofail() due to reset

In __iommu_group_set_domain_internal(), concurrent domain attachments are
rejected when any device in the group is recovering. This is necessary to
fence concurrent attachments to a multi-device group where devices might
share the same RID due to PCI DMA alias quirks, but triggers the WARN_ON in
__iommu_group_set_domain_nofail().

Other IOMMU_SET_DOMAIN_MUST_SUCCEED callers in detach/teardown paths, such
as __iommu_group_set_core_domain and __iommu_release_dma_ownership, should
not be rejected, as the domain would be freed anyway in these nofail paths
while group->domain is still pointing to it. So pci_dev_reset_iommu_done()
could trigger a UAF when re-attaching group->domain.

Honor the IOMMU_SET_DOMAIN_MUST_SUCCEED flag, allowing the callers through
the group->recovery_cnt fence, so as to update the group->domain pointer.
Instead add a gdev->blocked check in the device iteration loop, to prevent
any concurrent per-device detachment.
Comment 1 Mauro Matteo Cascella 2026-06-26 14:22:06 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062434-CVE-2026-52952-0cff@gregkh/T