In the Linux kernel, the following vulnerability has been resolved: vfio/type1: Unpin zero pages There's currently a reference count leak on the zero page. We increment the reference via pin_user_pages_remote(), but the page is later handled as an invalid/reserved page, therefore it's not accounted against the user and not unpinned by our put_pfn(). Introducing special zero page handling in put_pfn() would resolve the leak, but without accounting of the zero page, a single user could still create enough mappings to generate a reference count overflow. The zero page is always resident, so for our purposes there's no reason to keep it pinned. Therefore, add a loop to walk pages returned from pin_user_pages_remote() and unpin any zero pages.

[REJECTED CVE] A vulnerability was identified in the Linux kernel’s vfio/type1 subsystem, where a reference count leak on the zero page occurred due to improper handling in put_pfn(). The page was pinned via pin_user_pages_remote() but not properly unpinned, leading to a resource exhaustion risk. An attacker could exploit this by repeatedly mapping zero pages, potentially causing a reference count overflow, leading to undefined behavior or system instability.

Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.

In the Linux kernel, the following vulnerability has been resolved: vfio/type1: Unpin zero pages There's currently a reference count leak on the zero page. We increment the reference via pin_user_pages_remote(), but the page is later handled as an invalid/reserved page, therefore it's not accounted against the user and not unpinned by our put_pfn(). Introducing special zero page handling in put_pfn() would resolve the leak, but without accounting of the zero page, a single user could still create enough mappings to generate a reference count overflow. The zero page is always resident, so for our purposes there's no reason to keep it pinned. Therefore, add a loop to walk pages returned from pin_user_pages_remote() and unpin any zero pages.

Уязвимость компонентов vfio/type1 ядра операционной системы Linux, позволяющая нарушителю получить доступ к конфиденциальной информации

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Security update for the Linux Kernel

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