# CVE-2021-47254: linux: In the Linux kernel, the following vulnerability has been resolved:  gfs2: Fix use-after-free in gfs2_glock_shrink_sc...

CVE-2021-47254 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47254, released May 21, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-47254
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 21, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  gfs2: Fix use-after-free in gfs2_glock_shrink_scan  The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to remove the glock from the lru list in __gfs2_glock_put().  On the shrink scan path, the same flag is cleared under lru_lock but because of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the put side can be made without deleting the glock from the lru list.  Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to ensure correct behavior on both sides - clear GLF_LRU after list_del under lru_lock.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.46-1 | [DEBIAN-CVE-2021-47254](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47254.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.46-1 | [DEBIAN-CVE-2021-47254](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47254.md) | May 21, 2024 |
| Linux | linux Debian 14 | 5.10.46-1 | [DEBIAN-CVE-2021-47254](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47254.md) | May 21, 2024 |

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