{"id":"CVE-2026-74572","title":"btrfs: zoned: fix deadlock between metadata writeback and transaction commit","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: zoned: fix deadlock between metadata writeback and transaction commit\n\nWhen writing out metadata extent buffers in a zoned filesystem,\nbtree_writepages() holds f…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < 18577e77c2c8adaadf1f7c6e9bcd1c0b14e5dcdd","Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < c3320873e0c04ce7b746fc8fe948f07bbbbdec33","Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < deddd28fd83c264ee2ff5cd6b34449a9f1be6112","Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < 75859a7cd77cd2ddaddbcb963e3fcd34738953af","Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < 1ebe51c29fa9755d5b2fea28727c051117907cf8","Linux fca3a1cd3ba47f1815e0c0fcdc9aafaf02ee0a75","Linux >= 6.5.5 < 6.6","Linux 6.6"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-16T19:00:32.799131Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:05:56.826Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74572","references":[{"url":"https://git.kernel.org/stable/c/18577e77c2c8adaadf1f7c6e9bcd1c0b14e5dcdd"},{"url":"https://git.kernel.org/stable/c/c3320873e0c04ce7b746fc8fe948f07bbbbdec33"},{"url":"https://git.kernel.org/stable/c/deddd28fd83c264ee2ff5cd6b34449a9f1be6112"},{"url":"https://git.kernel.org/stable/c/75859a7cd77cd2ddaddbcb963e3fcd34738953af"},{"url":"https://git.kernel.org/stable/c/1ebe51c29fa9755d5b2fea28727c051117907cf8"}],"tags":["cve.org"],"epss":0.00346,"epssPercentile":0.26576,"ingestedAt":"2026-10-16T19:46:24.341Z","slug":"CVE-2026-74572","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: zoned: fix deadlock between metadata writeback and transaction commit\n\nWhen writing out metadata extent buffers in a zoned filesystem,\nbtree_writepages() holds fs_info->zoned_meta_io_lock across the whole\nwriteback loop, including the call to btrfs_check_meta_write_pointer() ->\ncheck_bg_is_active().\n\nFor the tree-log block group, check_bg_is_active() may fail to activate\nthe zone and fall back to btrfs_zone_finish_one_bg() to free an active\nzone. That path waits for the running transaction to commit while still\nholding zoned_meta_io_lock, but the committer needs that same lock to\nwrite out the tree extents, so the two tasks deadlock:\n\n  Task A (kworker, metadata writeback)      Task B (fsstress, transaction commit)\n  ------------------------------------      -------------------------------------\n  wb_workfn()                               btrfs_commit_transaction(T)\n   btree_writepages()                        btrfs_write_and_wait_transaction()\n    btrfs_zoned_meta_io_lock()                btrfs_write_marked_extents()\n    btrfs_check_meta_write_pointer()           btree_writepages()\n     check_bg_is_active() [treelog_bg]          btrfs_zoned_meta_io_lock()\n      btrfs_zone_finish_one_bg()               <blocks on zoned_meta_io_lock,\n       btrfs_zone_finish()                      held by Task A>\n        do_zone_finish()\n         btrfs_inc_block_group_ro()\n          btrfs_wait_for_commit()\n           <blocks waiting for commit\n            of transaction T, done by\n            Task B>\n\nThe sibling branch in check_bg_is_active() already drops zoned_meta_io_lock\naround do_zone_finish() for this exact reason. Do the same in the tree-log\nbranch: release the lock around btrfs_zone_finish_one_bg() and re-acquire\nit afterwards. The lock only protects fs_info->active_{meta,system}_bg,\nwhich this branch does not touch, and ctx->zoned_bg keeps a reference to\nthe block group across the unlock, so nothing is lost while the lock\nis dropped.\n\nThis hang occasionally reproduces with fstests generic/475 on a zoned\nbtrfs filesystem.\n\n## Affected\n\n- `Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < 18577e77c2c8adaadf1f7c6e9bcd1c0b14e5dcdd`\n- `Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < c3320873e0c04ce7b746fc8fe948f07bbbbdec33`\n- `Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < deddd28fd83c264ee2ff5cd6b34449a9f1be6112`\n- `Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < 75859a7cd77cd2ddaddbcb963e3fcd34738953af`\n- `Linux >= 13bb483d32abb6f8ebd40141d87eb68f11cc2dd2 < 1ebe51c29fa9755d5b2fea28727c051117907cf8`\n- `Linux fca3a1cd3ba47f1815e0c0fcdc9aafaf02ee0a75`\n- `Linux >= 6.5.5 < 6.6`\n- `Linux 6.6`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}