CVE-2026-23235
f2fs: fix out-of-bounds access in sysfs attribute read/write
Description
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix out-of-bounds access in sysfs attribute read/write Some f2fs sysfs attributes suffer from out-of-bounds memory access and incorrect handling of integer values whose size is not 4 bytes. For example: vm:~# echo 65537 > /sys/fs/f2fs/vde/carve_out vm:~# cat /sys/fs/f2fs/vde/carve_out 65537 vm:~# echo 4294967297 > /sys/fs/f2fs/vde/atgc_age_threshold vm:~# cat /sys/fs/f2fs/vde/atgc_age_threshold 1 carve_out maps to {struct f2fs_sb_info}->carve_out, which is a 8-bit integer. However, the sysfs interface allows setting it to a value larger than 255, resulting in an out-of-range update. atgc_age_threshold maps to {struct atgc_management}->age_threshold, which is a 64-bit integer, but its sysfs interface cannot correctly set values larger than UINT_MAX. The root causes are: 1. __sbi_store() treats all default values as unsigned int, which prevents updating integers larger than 4 bytes and causes out-of-bounds writes for integers smaller than 4 bytes. 2. f2fs_sbi_show() also assumes all default values are unsigned int, leading to out-of-bounds reads and incorrect access to integers larger than 4 bytes. This patch introduces {struct f2fs_attr}->size to record the actual size of the integer associated with each sysfs attribute. With this information, sysfs read and write operations can correctly access and update values according to their real data size, avoiding memory corruption and truncation.
INFO
Published Date :
March 4, 2026, 3:16 p.m.
Last Modified :
March 4, 2026, 6:08 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Review and apply the f2fs sysfs attribute patch.
- Verify correct integer size handling post-patch.
- Ensure sysfs read/write operations are safe.
References to Advisories, Solutions, and Tools
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CVE-2026-23235.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-23235 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
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stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-23235
weaknesses.
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Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Mar. 04, 2026
Action Type Old Value New Value Added Description In the Linux kernel, the following vulnerability has been resolved: f2fs: fix out-of-bounds access in sysfs attribute read/write Some f2fs sysfs attributes suffer from out-of-bounds memory access and incorrect handling of integer values whose size is not 4 bytes. For example: vm:~# echo 65537 > /sys/fs/f2fs/vde/carve_out vm:~# cat /sys/fs/f2fs/vde/carve_out 65537 vm:~# echo 4294967297 > /sys/fs/f2fs/vde/atgc_age_threshold vm:~# cat /sys/fs/f2fs/vde/atgc_age_threshold 1 carve_out maps to {struct f2fs_sb_info}->carve_out, which is a 8-bit integer. However, the sysfs interface allows setting it to a value larger than 255, resulting in an out-of-range update. atgc_age_threshold maps to {struct atgc_management}->age_threshold, which is a 64-bit integer, but its sysfs interface cannot correctly set values larger than UINT_MAX. The root causes are: 1. __sbi_store() treats all default values as unsigned int, which prevents updating integers larger than 4 bytes and causes out-of-bounds writes for integers smaller than 4 bytes. 2. f2fs_sbi_show() also assumes all default values are unsigned int, leading to out-of-bounds reads and incorrect access to integers larger than 4 bytes. This patch introduces {struct f2fs_attr}->size to record the actual size of the integer associated with each sysfs attribute. With this information, sysfs read and write operations can correctly access and update values according to their real data size, avoiding memory corruption and truncation. Added Reference https://git.kernel.org/stable/c/3a905e183c047577b154f08a78ac3039e9454703 Added Reference https://git.kernel.org/stable/c/438a405fbad6882df0e34b3e1a16839a71f04240 Added Reference https://git.kernel.org/stable/c/4ef30b9f1641c9e877792df6b049f1cf507d002d Added Reference https://git.kernel.org/stable/c/6a6c07a9b49e43f0df42d7118fc76aa555c73d98 Added Reference https://git.kernel.org/stable/c/98ea0039dbfdd00e5cc1b9a8afa40434476c0955 Added Reference https://git.kernel.org/stable/c/d4a594dd952df123cbdcdee9b9640d9d55e4a954 Added Reference https://git.kernel.org/stable/c/e85a99db9ab85dfc30d93b0ca0e9156f3127f55a Added Reference https://git.kernel.org/stable/c/eebd72cff518ac87e660aefb8a41224bd88c32ce