# CVE-2021-47533: linux: In the Linux kernel, the following vulnerability has been resolved:  drm/vc4: kms: Clear the HVS FIFO commit pointer...

CVE-2021-47533 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47533, released May 24, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-47533
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0022
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 24, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  drm/vc4: kms: Clear the HVS FIFO commit pointer once done  Commit 9ec03d7f1ed3 ("drm/vc4: kms: Wait on previous FIFO users before a commit") introduced a wait on the previous commit done on a given HVS FIFO.  However, we never cleared that pointer once done. Since drm_crtc_commit_put can free the drm_crtc_commit structure directly if we were the last user, this means that it can lead to a use-after free if we were to duplicate the state, and that stale pointer would even be copied to the new state.  Set the pointer to NULL once we're done with the wait so that we don't carry over a pointer to a free'd structure.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.15.15-1 | [DEBIAN-CVE-2021-47533](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47533.md) | May 24, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.15.15-1 | [DEBIAN-CVE-2021-47533](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47533.md) | May 24, 2024 |
| Linux | linux Debian 14 | 5.15.15-1 | [DEBIAN-CVE-2021-47533](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47533.md) | May 24, 2024 |

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