{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-49867", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-10-21T12:17:06.018Z", "datePublished": "2024-10-21T18:01:09.962Z", "dateUpdated": "2026-08-05T11:40:15.453Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:40:15.453Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: wait for fixup workers before stopping cleaner kthread during umount\n\nDuring unmount, at close_ctree(), we have the following steps in this order:\n\n1) Park the cleaner kthread - this doesn't destroy the kthread, it basically\n halts its execution (wake ups against it work but do nothing);\n\n2) We stop the cleaner kthread - this results in freeing the respective\n struct task_struct;\n\n3) We call btrfs_stop_all_workers() which waits for any jobs running in all\n the work queues and then free the work queues.\n\nSyzbot reported a case where a fixup worker resulted in a crash when doing\na delayed iput on its inode while attempting to wake up the cleaner at\nbtrfs_add_delayed_iput(), because the task_struct of the cleaner kthread\nwas already freed. This can happen during unmount because we don't wait\nfor any fixup workers still running before we call kthread_stop() against\nthe cleaner kthread, which stops and free all its resources.\n\nFix this by waiting for any fixup workers at close_ctree() before we call\nkthread_stop() against the cleaner and run pending delayed iputs.\n\nThe stack traces reported by syzbot were the following:\n\n BUG: KASAN: slab-use-after-free in __lock_acquire+0x77/0x2050 kernel/locking/lockdep.c:5065\n Read of size 8 at addr ffff8880272a8a18 by task kworker/u8:3/52\n\n CPU: 1 UID: 0 PID: 52 Comm: kworker/u8:3 Not tainted 6.12.0-rc1-syzkaller #0\n Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\n Workqueue: btrfs-fixup btrfs_work_helper\n Call Trace:\n \n __dump_stack lib/dump_stack.c:94 [inline]\n dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:377 [inline]\n print_report+0x169/0x550 mm/kasan/report.c:488\n kasan_report+0x143/0x180 mm/kasan/report.c:601\n __lock_acquire+0x77/0x2050 kernel/locking/lockdep.c:5065\n lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825\n __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]\n _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162\n class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]\n try_to_wake_up+0xb0/0x1480 kernel/sched/core.c:4154\n btrfs_writepage_fixup_worker+0xc16/0xdf0 fs/btrfs/inode.c:2842\n btrfs_work_helper+0x390/0xc50 fs/btrfs/async-thread.c:314\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310\n worker_thread+0x870/0xd30 kernel/workqueue.c:3391\n kthread+0x2f0/0x390 kernel/kthread.c:389\n ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n \n\n Allocated by task 2:\n kasan_save_stack mm/kasan/common.c:47 [inline]\n kasan_save_track+0x3f/0x80 mm/kasan/common.c:68\n unpoison_slab_object mm/kasan/common.c:319 [inline]\n __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345\n kasan_slab_alloc include/linux/kasan.h:247 [inline]\n slab_post_alloc_hook mm/slub.c:4086 [inline]\n slab_alloc_node mm/slub.c:4135 [inline]\n kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4187\n alloc_task_struct_node kernel/fork.c:180 [inline]\n dup_task_struct+0x57/0x8c0 kernel/fork.c:1107\n copy_process+0x5d1/0x3d50 kernel/fork.c:2206\n kernel_clone+0x223/0x880 kernel/fork.c:2787\n kernel_thread+0x1bc/0x240 kernel/fork.c:2849\n create_kthread kernel/kthread.c:412 [inline]\n kthreadd+0x60d/0x810 kernel/kthread.c:765\n ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n\n Freed by task 61:\n kasan_save_stack mm/kasan/common.c:47 [inline]\n kasan_save_track+0x3f/0x80 mm/kasan/common.c:68\n kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579\n poison_slab_object mm/kasan/common.c:247 [inline]\n __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264\n kasan_slab_free include/linux/kasan.h:230 [inline]\n slab_free_h\n---truncated---" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Reaching the bug needs local write activity on a mounted btrfs filesystem to queue fixup workers plus the local `umount(2)` → `close_ctree()` path; no remote or adjacent-network protocol handler is involved.\nAC:L - The attacker fully controls one side of the race and can keep `fs_info->fixup_workers` continuously saturated (dirtying file pages behind the FS's back via shared mmap/GUP writes) so a worker is essentially always in flight when unmount runs; where the attacker also triggers the unmount (removable btrfs media via udisks2, container teardown) they control both sides of the race.\nPR:L - No capability check exists on the path that queues the fixup work — `extent_writepage_io()` → `btrfs_writepage_cow_fixup()` is the plain writeback path and only requires an unprivileged user with write access to any file on a btrfs mount.\nUI:N - No victim action is required; the unmount that closes the race happens automatically at shutdown, container teardown, or media eject, and in the removable-media case the attacker performs it themselves.\nS:U - The use-after-free is on a kernel `task_struct` and its impact stays within the kernel's own security authority, crossing no VM, IOMMU, or sandbox boundary.\nC:H - The freed `task_struct` slab object can be reallocated with attacker-groomed content by spawning tasks, and `try_to_wake_up()` reads scheduler state and pointers out of it, providing a route to kernel memory disclosure.\nI:H - `try_to_wake_up()` writes into the freed object — `pi_lock` acquisition, `__state`/`on_rq` updates — and dispatches indirect calls through `p->sched_class`, giving both a write primitive and a control-flow-hijack primitive on a sprayable slab.\nA:H - This is a KASAN-confirmed slab-use-after-free reported by syzbot that oopses or panics the kernel during unmount, and the trigger can be repeated on every mount/unmount cycle." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/btrfs/disk-io.c" ], "versions": [ { "version": "7a97311de48d56af6db4c5819f95faf9b0b23b1a", "lessThan": "a71349b692ab34ea197949e13e3cc42570fe73d9", "status": "affected", "versionType": "git" }, { "version": "f4b1363cae43fef7c86c993b7ca7fe7d546b3c68", "lessThan": "70b60c8d9b42763d6629e44f448aa5d8ae477d61", "status": "affected", "versionType": "git" }, { "version": "f4b1363cae43fef7c86c993b7ca7fe7d546b3c68", "lessThan": "4c98fe0dfa2ae83c4631699695506d8941db4bfe", "status": "affected", "versionType": "git" }, { "version": "f4b1363cae43fef7c86c993b7ca7fe7d546b3c68", "lessThan": "9da40aea63f8769f28afb91aea0fac4cf6fbbb65", "status": "affected", "versionType": "git" }, { "version": "f4b1363cae43fef7c86c993b7ca7fe7d546b3c68", "lessThan": "ed87190e9d9c80aad220fb6b0b03a84d22e2c95b", "status": "affected", "versionType": "git" }, { "version": "f4b1363cae43fef7c86c993b7ca7fe7d546b3c68", "lessThan": "bf0de0f9a0544c11f96f93206da04ab87dcea1f4", "status": "affected", "versionType": "git" }, { "version": "f4b1363cae43fef7c86c993b7ca7fe7d546b3c68", "lessThan": "65d11eb276836d49003a8060cf31fa2284ad1047", "status": "affected", "versionType": "git" }, { "version": "f4b1363cae43fef7c86c993b7ca7fe7d546b3c68", "lessThan": "41fd1e94066a815a7ab0a7025359e9b40e4b3576", "status": "affected", "versionType": "git" }, { "version": "6026fd9da213daab95469356fe7fdcf29ae1a296", "status": "affected", "versionType": "git" }, { "version": "5.4.22", "lessThan": "5.4.285", "status": "affected", "versionType": "semver" }, { "version": "5.5.6", "lessThan": "5.6", "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/disk-io.c" ], "versions": [ { "version": "5.6", "status": "affected" }, { "version": "0", "lessThan": "5.6", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.285", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.227", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.168", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.113", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.55", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10.14", "lessThanOrEqual": "6.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.11.3", "lessThanOrEqual": "6.11.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12", "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": "5.4.22", "versionEndExcluding": "5.4.285" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.10.227" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "5.15.168" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.1.113" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.6.55" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.10.14" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.11.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.6", "versionEndExcluding": "6.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5.6" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a71349b692ab34ea197949e13e3cc42570fe73d9" }, { "url": "https://git.kernel.org/stable/c/70b60c8d9b42763d6629e44f448aa5d8ae477d61" }, { "url": "https://git.kernel.org/stable/c/4c98fe0dfa2ae83c4631699695506d8941db4bfe" }, { "url": "https://git.kernel.org/stable/c/9da40aea63f8769f28afb91aea0fac4cf6fbbb65" }, { "url": "https://git.kernel.org/stable/c/ed87190e9d9c80aad220fb6b0b03a84d22e2c95b" }, { "url": "https://git.kernel.org/stable/c/bf0de0f9a0544c11f96f93206da04ab87dcea1f4" }, { "url": "https://git.kernel.org/stable/c/65d11eb276836d49003a8060cf31fa2284ad1047" }, { "url": "https://git.kernel.org/stable/c/41fd1e94066a815a7ab0a7025359e9b40e4b3576" } ], "title": "btrfs: wait for fixup workers before stopping cleaner kthread during umount", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2024-49867", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-10-22T13:47:28.241887Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-10-22T13:48:52.483Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T22:22:34.501Z" } } ] } }