Use After Free Affecting linux-6.1 package, versions <6.1.164-1~deb11u1


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.12% (3rd percentile)

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  • Snyk IDSNYK-DEBIAN11-LINUX61-15654879
  • published16 Mar 2026
  • disclosed4 Mar 2026

Introduced: 4 Mar 2026

CVE-2026-23234  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Debian:11 linux-6.1 to version 6.1.164-1~deb11u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

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 Base Scores

version 3.1