UBUNTU-CVE-2026-68436: Low severity ubuntu/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: use kvzalloc to allocate struct dc struct dc has grown large over time (most of it the two inlined dcscratchspace copies) and now sits close to the page allocator's 4 MiB contiguous allocation limit. Its actual size is not fixed by the source alone, it also depends on the compiler and the .config, so it can easily cross 4 MiB, e.g. with a newer GCC or a config change. dccreate() allocates it with kzalloc(). Once struct dc exceeds 4 MiB the request is rounded up to order 11 (8 MiB), which is above MAXPAGEORDER, so the page allocator warns and returns NULL. dccreate() then fails, DM init fails and amdgpu probe aborts with -EINVAL: WARNING: mm/pagealloc.c:5197 at allocfrozenpagesnoprof+0x2f9/0x380 dccreate+0x38/0x660 [amdgpu] amdgpudminit+0x2d9/0x510 [amdgpu] dmhwinit+0x1b/0x90 [amdgpu] amdgpudeviceinit.cold+0x150d/0x1e13 [amdgpu] amdgpudriverloadkms+0x19/0x80 [amdgpu] amdgpupciprobe+0x1e2/0x4c0 [amdgpu] dccreate() then returns NULL and DM init fails, which aborts the whole GPU init and makes amdgpu probe fail with -EINVAL ("hwinit of IP block <dm> failed -22"), leaving the display unusable. The subsequent amdgpuirqput() warnings during teardown are just fallout of unwinding a half-initialized device. struct dc is a software-only bookkeeping structure that is never handed to hardware DMA and is only ever kept as an opaque pointer, so it does not require physically contiguous memory. Allocate it with kvzalloc() (and free it with kvfree()) so that the allocator can fall back to vmalloc() when a contiguous allocation of that size is not available, which also avoids the MAXPAGEORDER warning entirely. v2: - Rebase to amd-staging-drm-next. (cherry picked from commit 991e0516a8072f2292681c6ae98a924ab0e32575)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- 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-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-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-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-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-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - 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/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-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - 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 kernel drm/amd/displayto a version that resolves this vulnerability.Patch 991e0516a8072f2292681c6ae98a924ab0e32575
Event History
Frequently Asked Questions
Which systems are realistically affected by this failure?
Systems using the amdgpu driver are affected when their built kernel makes struct dc exceed the contiguous-allocation threshold. The size depends on the compiler and kernel configuration, so exposure can vary between builds.
What is required to trigger the issue?
No external attacker action is described. The failure occurs during amdgpu initialization when dc_create() requests an allocation that is rounded to 8 MiB, exceeding the page allocator's maximum order.
How can I tell whether a system is already affected?
Affected systems can log a page-allocation warning involving __alloc_frozen_pages_noprof and dc_create, followed by amdgpu display-manager initialization failure. The amdgpu probe may abort with -EINVAL and report "hw_init of IP block <dm> failed -22".
What is the operational impact?
The amdgpu GPU initialization fails, leaving the driver unable to probe the GPU. This can prevent the GPU from being initialized for use by the system.