CVE-2026-52952

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.

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• https://git.kernel.org/stable/c/5474e6e17a262db45c60575c73f70210f5c7001f
• https://git.kernel.org/stable/c/8fc289e809f3eb7e36cadc4684ab6fad747a5a93
• https://access.redhat.com/security/cve/CVE-2026-52952
• https://bugzilla.redhat.com/show_bug.cgi?id=2492422
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52952.json