CVE-2026-23234
Received
Received - Intake
Use-After-Free Vulnerability in Linux Kernel f2fs_write_end_io
Publication date: 2026-03-04
Last updated on: 2026-03-17
Assigner: kernel.org
Description
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.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | From 5.16 (inc) to 6.1.164 (exc) |
| linux | linux_kernel | From 5.11 (inc) to 5.15.201 (exc) |
| linux | linux_kernel | From 6.2 (inc) to 6.6.127 (exc) |
| linux | linux_kernel | From 6.7 (inc) to 6.12.74 (exc) |
| linux | linux_kernel | From 6.13 (inc) to 6.18.13 (exc) |
| linux | linux_kernel | From 6.19 (inc) to 6.19.3 (exc) |
| linux | linux_kernel | From 3.13 (inc) to 5.10.251 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-416 | The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. |
