Описание
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.
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.
Ссылки
- https://nvd.nist.gov/vuln/detail/CVE-2022-48700
- https://git.kernel.org/stable/c/5321908ef74fb593e0dbc8737d25038fc86c9986
- https://git.kernel.org/stable/c/578d644edc7d2c1ff53f7e4d0a25da473deb4a03
- https://git.kernel.org/stable/c/5d721bf222936f5cf3ee15ced53cc483ecef7e46
- https://git.kernel.org/stable/c/873aefb376bbc0ed1dd2381ea1d6ec88106fdbd4
CVE ID
Связанные уязвимости
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.
Уязвимость компонентов vfio/type1 ядра операционной системы Linux, позволяющая нарушителю получить доступ к конфиденциальной информации
