Monitor vulnerabilities like this one.
Sign up free to get alerted when software you use is affected.
Linux Kernel: Freeing File System Data Too Early
CVE-2026-23234
Summary
A bug in the Linux kernel's file system can cause data loss when a file is being written. This can happen when a file system is being unmounted quickly, and a process is still writing to it. To fix this issue, the kernel has been updated to ensure that file system data is not freed too early.
Original title
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 ...
Original description
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.
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.
- https://git.kernel.org/stable/c/0fb58aff0dafd6837cc91f4154f3ed6e020358fa
- https://git.kernel.org/stable/c/2f67ff1e15a8a4d0e4ffc6564ab20d03d7398fe9
- https://git.kernel.org/stable/c/505e1c0530db6152cab3feef8e3e4da3d3e358c9
- https://git.kernel.org/stable/c/995030be4ce6338c6ff814583c14166446a64008
- https://git.kernel.org/stable/c/a42f99be8a16b32a0bb91bb6dda212a6ad61be5d
- https://git.kernel.org/stable/c/acc2c97fc0005846e5cf11b5ba3189fef130c9b3
- https://git.kernel.org/stable/c/ce2739e482bce8d2c014d76c4531c877f382aa54
- https://git.kernel.org/stable/c/cf4a9e1bc8129eb63fda5f8bdcd8d87f0bd76f42
Published: 4 Mar 2026 · Updated: 13 Mar 2026 · First seen: 6 Mar 2026