{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-57896", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-01-11T14:45:42.029Z", "datePublished": "2025-01-15T13:05:48.310Z", "dateUpdated": "2026-08-05T11:46:49.998Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:46:49.998Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: flush delalloc workers queue before stopping cleaner kthread during unmount\n\nDuring the unmount path, at close_ctree(), we first stop the cleaner\nkthread, using kthread_stop() which frees the associated task_struct, and\nthen stop and destroy all the work queues. However after we stopped the\ncleaner we may still have a worker from the delalloc_workers queue running\ninode.c:submit_compressed_extents(), which calls btrfs_add_delayed_iput(),\nwhich in turn tries to wake up the cleaner kthread - which was already\ndestroyed before, resulting in a use-after-free on the task_struct.\n\nSyzbot reported this with the following stack traces:\n\n BUG: KASAN: slab-use-after-free in __lock_acquire+0x78/0x2100 kernel/locking/lockdep.c:5089\n Read of size 8 at addr ffff8880259d2818 by task kworker/u8:3/52\n\n CPU: 1 UID: 0 PID: 52 Comm: kworker/u8:3 Not tainted 6.13.0-rc1-syzkaller-00002-gcdd30ebb1b9f #0\n Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\n Workqueue: btrfs-delalloc 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:378 [inline]\n print_report+0x169/0x550 mm/kasan/report.c:489\n kasan_report+0x143/0x180 mm/kasan/report.c:602\n __lock_acquire+0x78/0x2100 kernel/locking/lockdep.c:5089\n lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849\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+0xc2/0x1470 kernel/sched/core.c:4205\n submit_compressed_extents+0xdf/0x16e0 fs/btrfs/inode.c:1615\n run_ordered_work fs/btrfs/async-thread.c:288 [inline]\n btrfs_work_helper+0x96f/0xc40 fs/btrfs/async-thread.c:324\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa66/0x1840 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:250 [inline]\n slab_post_alloc_hook mm/slub.c:4104 [inline]\n slab_alloc_node mm/slub.c:4153 [inline]\n kmem_cache_alloc_node_noprof+0x1d9/0x380 mm/slub.c:4205\n alloc_task_struct_node kernel/fork.c:180 [inline]\n dup_task_struct+0x57/0x8c0 kernel/fork.c:1113\n copy_process+0x5d1/0x3d50 kernel/fork.c:2225\n kernel_clone+0x223/0x870 kernel/fork.c:2807\n kernel_thread+0x1bc/0x240 kernel/fork.c:2869\n create_kthread kernel/kthread.c:412 [inline]\n kthreadd+0x60d/0x810 kernel/kthread.c:767\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 24:\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:582\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:233 [inline]\n slab_free_hook mm/slub.c:2338 [inline]\n slab_free mm/slub.c:4598 [inline]\n kmem_cache_free+0x195/0x410 mm/slub.c:4700\n put_task_struct include/linux/sched/task.h:144 [inline]\n delayed_put_task_struct+0x125/0x300 kernel/exit.c:227\n rcu_do_batch kernel/rcu/tree.c:2567 [inline]\n rcu_core+0xaaa/0x17a0 kernel/rcu/tree.c:2823\n handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:554\n run_ksoftirqd+0xca/0x130 kernel/softirq.c:943\n \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 - The attack requires local access to write compressed data to a mounted btrfs filesystem and the local unmount path (`umount(2)` → `close_ctree()`); there is no remote protocol handler involved.\nAC:L - The attacker fully controls one side of the race and can keep the `delalloc_workers` queue continuously saturated with compressed writeback so that a worker is essentially always in flight, making the UAF fire on any unmount rather than requiring a narrow timing window; where the attacker can also trigger the unmount (removable media via udisks2, container teardown) they control both sides.\nPR:L - Generating the compressed delalloc work needs only an unprivileged user with write access to a btrfs mount — per-inode compression is settable by the file owner via `chattr +c` (`inode_owner_or_capable`), and many distros mount with `compress=zstd` by default.\nUI:N - No victim action is needed; the unmount that closes the race occurs automatically at shutdown, on container teardown, or on 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 impacts only the kernel's own security authority, with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - The freed `task_struct` slab object can be reallocated with attacker-groomed content, and the wakeup path reads scheduler fields and pointers from it, giving a path to kernel memory disclosure.\nI:H - `try_to_wake_up()` writes into the freed object (`pi_lock` acquisition, `__state`/`on_rq` updates) and performs indirect calls through `p->sched_class`, providing write and control-flow-hijack primitives on a sprayable slab.\nA:H - The bug is a KASAN-confirmed slab-use-after-free reported by syzbot that reliably oopses or panics the kernel during unmount." } ] } ], "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": "fd340d0f68cc87badfc9efcb226f23a5428826a0", "lessThan": "a2718ed1eb8c3611b63f8933c7e68c8821fe2808", "status": "affected", "versionType": "git" }, { "version": "fd340d0f68cc87badfc9efcb226f23a5428826a0", "lessThan": "63f4b594a688bf922e8691f0784679aa7af7988c", "status": "affected", "versionType": "git" }, { "version": "fd340d0f68cc87badfc9efcb226f23a5428826a0", "lessThan": "1ea629e7bb2fb40555e5e01a1b5095df31287017", "status": "affected", "versionType": "git" }, { "version": "fd340d0f68cc87badfc9efcb226f23a5428826a0", "lessThan": "35916b2f96505a18dc7242a115611b718d9de725", "status": "affected", "versionType": "git" }, { "version": "fd340d0f68cc87badfc9efcb226f23a5428826a0", "lessThan": "d77a3a99b53d12c061c007cdc96df38825dee476", "status": "affected", "versionType": "git" }, { "version": "fd340d0f68cc87badfc9efcb226f23a5428826a0", "lessThan": "f10bef73fb355e3fc85e63a50386798be68ff486", "status": "affected", "versionType": "git" } ] }, { "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": "5.0", "status": "affected" }, { "version": "0", "lessThan": "5.0", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.233", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.176", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.124", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.70", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.9", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13", "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": "5.0", "versionEndExcluding": "5.10.233" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "5.15.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.1.124" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.6.70" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.12.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a2718ed1eb8c3611b63f8933c7e68c8821fe2808" }, { "url": "https://git.kernel.org/stable/c/63f4b594a688bf922e8691f0784679aa7af7988c" }, { "url": "https://git.kernel.org/stable/c/1ea629e7bb2fb40555e5e01a1b5095df31287017" }, { "url": "https://git.kernel.org/stable/c/35916b2f96505a18dc7242a115611b718d9de725" }, { "url": "https://git.kernel.org/stable/c/d77a3a99b53d12c061c007cdc96df38825dee476" }, { "url": "https://git.kernel.org/stable/c/f10bef73fb355e3fc85e63a50386798be68ff486" } ], "title": "btrfs: flush delalloc workers queue before stopping cleaner kthread during unmount", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2024-57896", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2025-02-11T15:40:57.951586Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-02-11T15:45:19.574Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:55:11.913Z" } } ] } }