{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74572", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.917Z", "datePublished": "2026-08-15T12:28:11.328Z", "dateUpdated": "2026-08-17T05:48:51.651Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:48:51.651Z" }, "descriptions": [ { "lang": "en", "value": "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 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() \n do_zone_finish()\n btrfs_inc_block_group_ro()\n btrfs_wait_for_commit()\n \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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - On storage servers exporting a zoned btrfs volume via nfsd or ksmbd, remote client write/fsync I/O reaches btrfs_commit_transaction() and btree_writepages() on the server kernel without any local syscall access.\nAC:L - The attacker controls both deadlock participants by driving concurrent metadata dirtying/writeback and transaction commits (reproduced with fsstress/fstests generic/475); the kworker writeback side is a direct result of attacker-generated btree dirty pages.\nPR:N - Exploitation requires only network write access to an NFS or SMB export of the zoned btrfs filesystem; no local account, capability, or init-namespace privilege is needed when the export permits client writes.\nUI:N - The deadlock is triggered entirely by the attacker's own concurrent write and sync I/O; no victim must mount a filesystem, open a file, or perform any interactive action.\nS:U - The mutex deadlock freezes btrfs metadata I/O within the same host kernel security authority; it does not cross a VM, IOMMU, or sandbox boundary.\nC:N - This is a lock-ordering deadlock with no memory corruption, out-of-bounds access, use-after-free, or information disclosure of any kind.\nI:N - The bug causes tasks to block indefinitely on locks but does not corrupt, modify, or overwrite any data or enable arbitrary writes or code execution.\nA:H - The circular wait between zoned_meta_io_lock and btrfs_wait_for_commit() permanently hangs metadata writeback and transaction commit, freezing all I/O on the affected zoned btrfs filesystem." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/btrfs/zoned.c" ], "versions": [ { "version": "13bb483d32abb6f8ebd40141d87eb68f11cc2dd2", "lessThan": "18577e77c2c8adaadf1f7c6e9bcd1c0b14e5dcdd", "status": "affected", "versionType": "git" }, { "version": "13bb483d32abb6f8ebd40141d87eb68f11cc2dd2", "lessThan": "c3320873e0c04ce7b746fc8fe948f07bbbbdec33", "status": "affected", "versionType": "git" }, { "version": "13bb483d32abb6f8ebd40141d87eb68f11cc2dd2", "lessThan": "deddd28fd83c264ee2ff5cd6b34449a9f1be6112", "status": "affected", "versionType": "git" }, { "version": "13bb483d32abb6f8ebd40141d87eb68f11cc2dd2", "lessThan": "75859a7cd77cd2ddaddbcb963e3fcd34738953af", "status": "affected", "versionType": "git" }, { "version": "13bb483d32abb6f8ebd40141d87eb68f11cc2dd2", "lessThan": "1ebe51c29fa9755d5b2fea28727c051117907cf8", "status": "affected", "versionType": "git" }, { "version": "fca3a1cd3ba47f1815e0c0fcdc9aafaf02ee0a75", "status": "affected", "versionType": "git" }, { "version": "6.5.5", "lessThan": "6.6", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/btrfs/zoned.c" ], "versions": [ { "version": "6.6", "status": "affected" }, { "version": "0", "lessThan": "6.6", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.151", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.103", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.6.151" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.12.103" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.18.44" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "7.1.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "7.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5.5" } ] } ] } ], "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" } ], "title": "btrfs: zoned: fix deadlock between metadata writeback and transaction commit", "x_generator": { "engine": "bippy-1.2.0" } } } }