CVE-2026-23234

NameCVE-2026-23234
DescriptionIn 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-4498-1, DLA-4499-1, DSA-6162-1, DSA-6163-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)bullseye5.10.223-1vulnerable
bullseye (security)5.10.251-1fixed
bookworm6.1.159-1vulnerable
bookworm (security)6.1.164-1fixed
trixie6.12.73-1vulnerable
trixie (security)6.12.74-2fixed
forky, sid6.19.8-1fixed
linux-6.1 (PTS)bullseye (security)6.1.164-1~deb11u1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebullseye5.10.251-1DLA-4498-1
linuxsourcebookworm6.1.164-1DSA-6163-1
linuxsourcetrixie6.12.74-2DSA-6162-1
linuxsource(unstable)6.18.13-1
linux-6.1sourcebullseye6.1.164-1~deb11u1DLA-4499-1

Notes

https://git.kernel.org/linus/ce2739e482bce8d2c014d76c4531c877f382aa54 (7.0-rc1)

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