Linux Kernel CVE-2026-23234
HIGHCVSS VectorNVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3DescriptionNVD
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to avoid UAF in f2fs_write_end_io()
As syzbot reported an use-after-free issue in f2fs_write_end_io().
It is caused by below race condition:
loop device umount
- worker_thread
- loop_process_work
- do_req_filebacked
- lo_rw_aio
- lo_rw_aio_complete
- blk_mq_end_request
- blk_update_request
- f2fs_write_end_io
- dec_page_count
- folio_end_writeback
- kill_f2fs_super
- kill_block_super
- f2fs_put_super
: free(sbi) : get_pages(, F2FS_WB_CP_DATA) accessed sbi which is freed
In kill_f2fs_super(), we will drop all page caches of f2fs inodes before call free(sbi), it guarantee that all folios should end its writeback, so it should be safe to access sbi before last folio_end_writeback().
Let's relocate ckpt thread wakeup flow before folio_end_writeback() to resolve this issue.
AnalysisAI
A use-after-free vulnerability in the Linux kernel's f2fs filesystem allows a local attacker with user privileges to trigger memory corruption and crash the system through a race condition between I/O completion and filesystem unmount operations. The vulnerability occurs when a loop device completes write operations concurrently with an unmount that frees filesystem structures still being accessed by pending I/O handlers. …
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RemediationAI
Within 7 days: Identify all affected systems and apply vendor patches promptly. If patching is delayed, consider network segmentation to limit exposure.
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