CVE-2025-38709

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Source
https://cve.org/CVERecord?id=CVE-2025-38709
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-38709.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2025-38709
Downstream
Related
Published
2025-09-04T15:32:59.818Z
Modified
2026-03-20T12:42:59.624739Z
Summary
loop: Avoid updating block size under exclusive owner
Details

In the Linux kernel, the following vulnerability has been resolved:

loop: Avoid updating block size under exclusive owner

Syzbot came up with a reproducer where a loop device block size is changed underneath a mounted filesystem. This causes a mismatch between the block device block size and the block size stored in the superblock causing confusion in various places such as fs/buffer.c. The particular issue triggered by syzbot was a warning in _getblkslow() due to requested buffer size not matching block device block size.

Fix the problem by getting exclusive hold of the loop device to change its block size. This fails if somebody (such as filesystem) has already an exclusive ownership of the block device and thus prevents modifying the loop device under some exclusive owner which doesn't expect it.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38709.json",
    "cna_assigner": "Linux"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
89e4fdecb51cf5535867026274bc97de9480ade5
Fixed
457d2c5e112fd08dc1039b1ae39a83ec1782360d
Fixed
139a000d20f2f38ce34296feddd641d730fe1c08
Fixed
b928438cc87c0bf7ae078e4b7b6e14261e84c5c5
Fixed
5d67b30aefeb7a949040bbb1b4e3b84c5d29a624
Fixed
7e49538288e523427beedd26993d446afef1a6fb

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-38709.json"