CVE-2025-68240
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-16

Last updated on: 2025-12-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: nilfs2: avoid having an active sc_timer before freeing sci Because kthread_stop did not stop sc_task properly and returned -EINTR, the sc_timer was not properly closed, ultimately causing the problem [1] reported by syzbot when freeing sci due to the sc_timer not being closed. Because the thread sc_task main function nilfs_segctor_thread() returns 0 when it succeeds, when the return value of kthread_stop() is not 0 in nilfs_segctor_destroy(), we believe that it has not properly closed sc_timer. We use timer_shutdown_sync() to sync wait for sc_timer to shutdown, and set the value of sc_task to NULL under the protection of lock sc_state_lock, so as to avoid the issue caused by sc_timer not being properly shutdowned. [1] ODEBUG: free active (active state 0) object: 00000000dacb411a object type: timer_list hint: nilfs_construction_timeout Call trace: nilfs_segctor_destroy fs/nilfs2/segment.c:2811 [inline] nilfs_detach_log_writer+0x668/0x8cc fs/nilfs2/segment.c:2877 nilfs_put_super+0x4c/0x12c fs/nilfs2/super.c:509
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Meta Information
Published
2025-12-16
Last Modified
2025-12-18
Generated
2026-05-07
AI Q&A
2025-12-16
EPSS Evaluated
2026-05-05
NVD
CVE-2025-68240
EUVD
EUVD-2025-203656
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, update the Linux kernel to a version where the nilfs2 issue with sc_timer and sc_task has been fixed. The fix involves proper shutdown of sc_timer using timer_shutdown_sync() and setting sc_task to NULL under lock protection. Applying the official patch or kernel update that addresses this issue is the recommended immediate step.


Can you explain this vulnerability to me?

This vulnerability in the Linux kernel's nilfs2 filesystem involves improper handling of a timer (sc_timer) when freeing a structure (sci). Specifically, the function kthread_stop did not properly stop the sc_task thread, causing the sc_timer to remain active and not be closed correctly. This improper shutdown of the timer can lead to issues such as use-after-free or other memory management problems during the freeing process.


How can this vulnerability impact me? :

The vulnerability can cause improper shutdown of a timer in the nilfs2 filesystem, potentially leading to system instability, crashes, or memory corruption. This could affect the reliability and security of systems using the affected Linux kernel version, possibly resulting in denial of service or other unintended behavior.


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