Linux Kernel up to 7.1.5/7.2-rc4 IOMMU iommu_dma_free_iova.isra amd_iommu_domain_flush_pages locking

Summaryinfo

A vulnerability has been found in Linux Kernel up to 7.1.5/7.2-rc4 and classified as very critical. This affects the function amd_iommu_domain_flush_pages of the file iommu_dma_free_iova.isra of the component IOMMU. Performing a manipulation results in locking. This vulnerability is reported as CVE-2026-68347. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 7.1.5/7.2-rc4. This affects the function amd_iommu_domain_flush_pages of the file iommu_dma_free_iova.isra of the component IOMMU. The manipulation with an unknown input leads to a locking vulnerability. CWE is classifying the issue as CWE-667. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: iommu/amd: Fix IRQ unsafe locking in gdom allocation Lockdep complains: [ 259.410489] ===================================================== [ 259.417287] WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected [ 259.424667] 7.0.0-g51db1d8d2113 #54 Not tainted [ 259.429718] ----------------------------------------------------- [ 259.436516] qemu-system-x86/10143 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 259.444670] ff3b2b1c60305170 (&xa->xa_lock#25){+.+.}-{3:3}, at: __domain_flush_pages+0x17c/0x4b0 [ 259.454485] and this task is already holding: [ 259.460991] ff3b2b1c98504cc0 (&domain->lock){-.-.}-{3:3}, at: amd_iommu_iotlb_sync+0x25/0x60 [ 259.470408] which would create a new lock dependency: [ 259.476041] (&domain->lock){-.-.}-{3:3} -> (&xa->xa_lock#25){+.+.}-{3:3} [ 259.483615] but this new dependency connects a HARDIRQ-irq-safe lock: [ 259.492447] (&domain->lock){-.-.}-{3:3} [ 259.492449] ... which became HARDIRQ-irq-safe at: [ 259.503705] lock_acquire+0xb6/0x2e0 [ 259.507790] _raw_spin_lock_irqsave+0x3e/0x60 [ 259.512748] amd_iommu_flush_iotlb_all+0x20/0x50 [ 259.517996] iommu_dma_free_iova.isra.0+0x1b8/0x1e0 [ 259.523534] __iommu_dma_unmap+0xc2/0x140 [ 259.528100] iommu_dma_unmap_phys+0x55/0xc0 [ 259.532863] dma_unmap_phys+0x274/0x2e0 [ 259.537238] dma_unmap_page_attrs+0x17/0x30 [ 259.542000] nvme_unmap_data+0x13e/0x280 [ 259.546473] nvme_pci_complete_batch+0x45/0x70 [ 259.551524] nvme_irq+0x83/0x90 [ 259.555123] __handle_irq_event_percpu+0x92/0x360 [ 259.560466] handle_irq_event+0x39/0x80 [ 259.564841] handle_edge_irq+0xb2/0x1a0 [ 259.569214] __common_interrupt+0x4e/0x130 [ 259.573882] common_interrupt+0x88/0xa0 [ 259.578256] asm_common_interrupt+0x27/0x40 [ 259.583019] cpuidle_enter_state+0x119/0x5d0 [ 259.587877] cpuidle_enter+0x2e/0x50 [ 259.591962] do_idle+0x153/0x2c0 [ 259.595657] cpu_startup_entry+0x29/0x30 [ 259.600128] start_secondary+0x118/0x150 [ 259.604601] common_startup_64+0x13e/0x141 [ 259.609266] to a HARDIRQ-irq-unsafe lock: [ 259.615384] (&xa->xa_lock#25){+.+.}-{3:3} [ 259.615386] ... which became HARDIRQ-irq-unsafe at: [ 259.627039] ... [ 259.627039] lock_acquire+0xb6/0x2e0 [ 259.633071] _raw_spin_lock+0x2f/0x50 [ 259.637250] amd_iommu_alloc_domain_nested+0x140/0x3c0 [ 259.643078] iommufd_hwpt_alloc+0x272/0x800 [iommufd] [ 259.648813] iommufd_fops_ioctl+0x14e/0x200 [iommufd] [ 259.654547] __x64_sys_ioctl+0x9d/0xf0 ... Since amd_iommu_domain_flush_pages() necessarily holds domain->lock to do the flush, switch the allocation side in gdom_info_load_or_alloc_locked() to HARDIRQ-safe allocation. The IOMMU_DESTROY->free path has the same issue, so switch that path to HARDIRQ-safe locking as well.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-68347 since 07/30/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/10/2026).

Upgrading to version 7.1.6 or 7.2-rc5 eliminates this vulnerability. Applying the patch e0c78cdf35af3ada05f9309f4641e9f83c945dbd/0db3a430d9681fdb29890bef6934cd89cd1745d0 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4
• 7.1.5
• 7.2-rc1
• 7.2-rc2
• 7.2-rc3
• 7.2-rc4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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