CVE-2026-68459: f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix potential deadlock in gcmerge path of f2fsbalancefs()
When we mount device w/ gcmerge mount option, we may suffer below potential deadlock:
Kworker GC trehad Truncator - f2fswritecachepages - f2fswritesingledatapage - f2fsdowritedatapage - foliostartwriteback --- set writeback flag on folio - f2fsoutplacewritedata : cached folio in internal bio cache - f2fsbalancefs - wakeup(gcthread) : wake up gc thread to run foreground GC - finishwait(fggcwq) : wait on the waitqueue --- wait on GC thread to finish the work - truncateinodepagesrange - filemapgetfolio(, FGPLOCK) --- lock folio - truncateinodepartialfolio - foliowaitwriteback --- wait on writeback being cleared - dogarbagecollect - movedatapage - f2fsgetlockdatafolio - lock on folio --- blocked on folio's lock
In order to avoid such deadlock, let's call below functions to commit cached bios in GCMERGE path of f2fsbalancefs() as the same as we did in NOGCMERGE path. - f2fssubmitmergedwrite(sbi, DATA); - f2fssubmitallmergedipuwrites(sbi);
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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In the GC_MERGE path of f2fs_balance_fs(), commit cached bios by calling f2fs_submit_all_merged_ipu_writes(sbi) and f2fs_submit_merged_write(sbi, DATA), as already done in the NOGC_MERGE path, to avoid the potential deadlock.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-68459?
CVE-2026-68459 has a risk rating of 37.
What does CVE-2026-68459 affect?
CVE-2026-68459 affects the Linux kernel, specifically in the f2fs filesystem's gc_merge path.
How do I fix CVE-2026-68459?
To fix CVE-2026-68459, update to the latest version of the Linux kernel where the vulnerability has been patched.
What is the nature of the vulnerability in CVE-2026-68459?
CVE-2026-68459 is a potential deadlock issue that may occur when using the gc_merge mount option.
When was CVE-2026-68459 published?
CVE-2026-68459 was published on August 15, 2026.