UBUNTU-CVE-2026-80618: Medium severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: drm/amdkfd: Avoid double-unpin of DOORBELL/MMIO BOs on free amdgpuamdkfdgpuvmfreememoryofgpu() unpinned DOORBELL and MMIO remap BOs (which are pinned at allocation time) before checking whether the BO is still mapped to the GPU. When the BO is still mapped, the function returns -EBUSY and leaves the BO alive, but it has already been unpinned. The BO is then unpinned again when it is finally freed during process teardown, triggering a ttmbounpin() underflow warning: WARNING: CPU: 18 PID: 15066 at ttm/ttmbo.c:650 amdttmbounpin+0x6d/0x80 [amdttm] Workqueue: kfdprocesswq kfdprocesswqrelease [amdgpu] RIP: 0010:amdttmbounpin+0x6d/0x80 [amdttm] Call Trace: amdgpubounpin+0x1a/0x90 [amdgpu] amdgpuamdkfdgpuvmunpinbo+0x31/0xb0 [amdgpu] amdgpuamdkfdgpuvmfreememoryofgpu+0x3bf/0x460 [amdgpu] kfdprocessfreeoutstandingkfdbos+0xd4/0x170 [amdgpu] kfdprocesswqrelease+0x109/0x1b0 [amdgpu] processonework+0x1e2/0x3b0 workerthread+0x50/0x3a0 kthread+0xdd/0x100 retfromfork+0x29/0x50 Move the unpin after the mappedtogpumemory check so it only happens once we are committed to freeing the BO. (cherry picked from commit 927c5b2defb9b09856444d94bebfd056a002bd75)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-147.147 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70 - Upgrade
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ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79 - Upgrade
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ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 6.8.0-1069.76 - Upgrade
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ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79 - Upgrade
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ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 6.8.0-1066.74 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 6.8.0-1052.56 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1067.68 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-147.147.1 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1064.67 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1033.38 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1062.63 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-147.147+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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Linux kernelto a version that resolves this vulnerability.Patch 927c5b2defb9b09856444d94bebfd056a002bd75
Event History
Frequently Asked Questions
Which systems are realistically exposed to this issue?
Systems running one of the listed Ubuntu kernel packages are relevant only if they use the AMDGPU/KFD path involving DOORBELL or MMIO remap buffer objects. The issue occurs during GPU virtual-memory buffer-object cleanup.
What condition triggers the warning?
The affected cleanup function unpins a DOORBELL or MMIO remap buffer object before determining whether it is still mapped to GPU memory. If it remains mapped, cleanup returns -EBUSY while leaving the object alive; a later process teardown unpins it again and triggers the underflow warning.
How can an administrator tell whether the issue has occurred?
Affected systems may log a ttm_bo_unpin() underflow warning during kfd_process_wq_release processing. The supplied trace includes amdttm_bo_unpin, amdgpu_amdkfd_gpuvm_free_memory_of_gpu, and kfd_process_free_outstanding_kfd_bos.