# CVE-2022-48700: linux: In the Linux kernel, the following vulnerability has been resolved:  vfio/type1: Unpin zero pages  There's currently...

CVE-2022-48700 is fixed in linux on 1 platform, first by CVE-2022-48700, released May 3, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-48700
- Priority: Routine
- CVSS: n/a
- EPSS: n/a
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 3, 2024

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 11.6 (bullseye) | 5.10.148-1 | [CVE-2022-48700](https://patchblox.com/security/data/fix/linux/cve-2022-48700.md) | May 3, 2024 |
| Linux | linux Debian 12.15 (bookworm) | 5.19.11-1 | [CVE-2022-48700](https://patchblox.com/security/data/fix/linux/cve-2022-48700.md) | May 3, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.19.11-1 | [CVE-2022-48700](https://patchblox.com/security/data/fix/linux/cve-2022-48700.md) | May 3, 2024 |

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