Linux Kernel Hv Gpci denial of service

Summaryinfo

A vulnerability labeled as critical has been found in Linux Kernel. This issue affects the function processor_bus_topology_show/processor_config_show/affinity_domain_via_virtual_processor_show/affinity_domain_via_domain_show of the component Hv Gpci. The manipulation results in denial of service. This vulnerability was named CVE-2026-64070. The attack needs to be approached locally. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel (the affected version unknown). Affected is the function processor_bus_topology_show/processor_config_show/affinity_domain_via_virtual_processor_show/affinity_domain_via_domain_show of the component Hv Gpci. The manipulation with an unknown input leads to a denial of service vulnerability. CWE is classifying the issue as CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: powerpc/hv-gpci: fix preempt count leak in sysfs show paths Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb) (which calls preempt_disable()) but only call the matching put_cpu_var() on the error path under the 'out:' label. Every successful read leaks one preempt_disable(): processor_bus_topology_show() processor_config_show() affinity_domain_via_virtual_processor_show() affinity_domain_via_domain_show() (affinity_domain_via_partition_show() was already correct.) On a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and eventually return to userspace with preemption still disabled. The next user-mode page fault then hits faulthandler_disabled() == 1, gets forced to SIGSEGV, and the resulting coredump trips 'BUG: scheduling while atomic' in call_usermodehelper_exec -> wait_for_completion_state -> schedule: BUG: scheduling while atomic: <task>/<pid>/0x00000004 ... __schedule_bug+0x6c/0x90 __schedule+0x58c/0x13a0 schedule+0x48/0x1a0 schedule_timeout+0x104/0x170 wait_for_completion_state+0x16c/0x330 call_usermodehelper_exec+0x254/0x2d0 vfs_coredump+0x1050/0x2590 get_signal+0xb9c/0xc80 do_notify_resume+0xf8/0x470 Add an out_success label that calls put_cpu_var() before returning the byte count, mirroring affinity_domain_via_partition_show().

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-64070 since 07/19/2026. The exploitability is told to be easy. The attack needs to be approached locally. There are known technical details, but no exploit is available.

Applying the patch 903409000a07ac8e31ffedeb8516f4f8d67150c8 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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