CVE-2022-48700

low

Description

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.

References

https://git.kernel.org/stable/c/873aefb376bbc0ed1dd2381ea1d6ec88106fdbd4

https://git.kernel.org/stable/c/5d721bf222936f5cf3ee15ced53cc483ecef7e46

https://git.kernel.org/stable/c/578d644edc7d2c1ff53f7e4d0a25da473deb4a03

https://git.kernel.org/stable/c/5321908ef74fb593e0dbc8737d25038fc86c9986

Details

Source: Mitre, NVD

Published: 2024-05-03

Updated: 2024-05-06

Risk Information

CVSS v2

Base Score: 1.7

Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:P

Severity: Low

CVSS v3

Base Score: 3.3

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Severity: Low