CVE-2025-38579
HIGHCVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Description
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix KMSAN uninit-value in extent_info usage KMSAN reported a use of uninitialized value in `__is_extent_mergeable()` and `__is_back_mergeable()` via the read extent tree path. The root cause is that `get_read_extent_info()` only initializes three fields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the remaining fields uninitialized. This leads to undefined behavior when those fields are accessed later, especially during extent merging. Fix it by zero-initializing the `extent_info` struct before population.
Analysis
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix KMSAN uninit-value in extent_info usage KMSAN reported a use of uninitialized value in __is_extent_mergeable() and. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. This Use of Uninitialized Resource vulnerability could allow attackers to access uninitialized memory causing crashes or information disclosure.
Technical Context
This vulnerability is classified as Use of Uninitialized Resource (CWE-908), which allows attackers to access uninitialized memory causing crashes or information disclosure. In the Linux kernel, the following vulnerability has been resolved: f2fs: fix KMSAN uninit-value in extent_info usage KMSAN reported a use of uninitialized value in `__is_extent_mergeable()` and `__is_back_mergeable()` via the read extent tree path. The root cause is that `get_read_extent_info()` only initializes three fields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the remaining fields uninitialized. This leads to undefined behavior when those fields are accessed later, especially during extent merging. Fix it by zero-initializing the `extent_info` struct before population. Affected products include: Linux Linux Kernel, Debian Debian Linux.
Affected Products
Linux Linux Kernel, Debian Debian Linux.
Remediation
A vendor patch is available. Apply the latest security update as soon as possible. Initialize all variables, use compiler warnings for uninitialized access, use memory-safe languages.
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External POC / Exploit Code
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