# CVE-2021-47004: linux: In the Linux kernel, the following vulnerability has been resolved:  f2fs: fix to avoid touching checkpointed data in...

CVE-2021-47004 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47004, released February 28, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-47004
- Priority: High
- CVSS: 7.1 (high)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 28, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  f2fs: fix to avoid touching checkpointed data in get_victim()  In CP disabling mode, there are two issues when using LFS or SSR | AT_SSR mode to select victim:  1. LFS is set to find source section during GC, the victim should have no checkpointed data, since after GC, section could not be set free for reuse.  Previously, we only check valid chpt blocks in current segment rather than section, fix it.  2. SSR | AT_SSR are set to find target segment for writes which can be fully filled by checkpointed and newly written blocks, we should never select such segment, otherwise it can cause panic or data corruption during allocation, potential case is described as below:   a) target segment has 'n' (n < 512) ckpt valid blocks  b) GC migrates 'n' valid blocks to other segment (segment is still     in dirty list)  c) GC migrates '512 - n' blocks to target segment (segment has 'n'     cp_vblocks and '512 - n' vblocks)  d) If GC selects target segment via {AT,}SSR allocator, however there     is no free space in targe segment.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.10.38-1 | [DEBIAN-CVE-2021-47004](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47004.md) | Feb 28, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.10.38-1 | [DEBIAN-CVE-2021-47004](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47004.md) | Feb 28, 2024 |
| Linux | linux Debian 14 | 5.10.38-1 | [DEBIAN-CVE-2021-47004](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47004.md) | Feb 28, 2024 |

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