CVE-2025-38709 Details
Description
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 __getblk_slow() 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.
A vulnerability in the Linux kernel's loop device management has been addressed. The issue arose when the block size of a loop device was altered while a filesystem was mounted, creating a discrepancy between the block device's block size and the block size recorded in the superblock. This mismatch led to confusion in several kernel functions, particularly __getblk_slow(), which generated a warning due to a buffer size request that did not align with the block device's block size. The vulnerability has been fixed by ensuring that changes to the loop device's block size can only be made when the device is not under exclusive ownership, thereby preventing unexpected modifications that could disrupt filesystem operations.
Users can update to the latest version of the Linux kernel where this vulnerability has been fixed. Instructions for downloading the patched kernel can be found on the official Linux kernel website.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
No SSVC data is available for this CVE.
References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://git.kernel.org/stable/c/139a000d20f2f38ce34296feddd641d730fe1c08 | kernel.org | Patch |
| https://git.kernel.org/stable/c/457d2c5e112fd08dc1039b1ae39a83ec1782360d | kernel.org | Patch |
| https://git.kernel.org/stable/c/5d67b30aefeb7a949040bbb1b4e3b84c5d29a624 | kernel.org | Patch |
| https://git.kernel.org/stable/c/7e49538288e523427beedd26993d446afef1a6fb | kernel.org | Patch |
| https://git.kernel.org/stable/c/b928438cc87c0bf7ae078e4b7b6e14261e84c5c5 | kernel.org | Patch |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| NVD-CWE-noinfo | Insufficient Information to Classify Weakness | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| linux linux kernel | < 6.6.109 >= 6.7, < 6.12.43 >= 6.13, < 6.15.11 >= 6.16, < 6.16.2 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | kernel.org |
| Dec 3, 2025 | Initial Analysis | [email protected] |
| Oct 2, 2025 | CVE Modified | kernel.org |
| Sep 25, 2025 | CVE Modified | kernel.org |
| Sep 4, 2025 | New CVE Received | kernel.org |