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CVE-2024-49867— btrfs: wait for fixup workers before stopping cleaner kthread during umount

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于在卸载过程中未等待fixup工作完成就停止cleaner kthread，可能导致使用已释放的cleaner kthread任务结构时发生崩溃。

CVSS 7.8 · High EPSS 0.30% · P21

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 21

VendorProduct Version RangeStatus
Linux Linux 7a97311de48d56af6db4c5819f95faf9b0b23b1a< a71349b692ab34ea197949e13e3cc42570fe73d9 affected
f4b1363cae43fef7c86c993b7ca7fe7d546b3c68< 70b60c8d9b42763d6629e44f448aa5d8ae477d61 affected
f4b1363cae43fef7c86c993b7ca7fe7d546b3c68< 4c98fe0dfa2ae83c4631699695506d8941db4bfe affected
f4b1363cae43fef7c86c993b7ca7fe7d546b3c68< 9da40aea63f8769f28afb91aea0fac4cf6fbbb65 affected
f4b1363cae43fef7c86c993b7ca7fe7d546b3c68< ed87190e9d9c80aad220fb6b0b03a84d22e2c95b affected
f4b1363cae43fef7c86c993b7ca7fe7d546b3c68< bf0de0f9a0544c11f96f93206da04ab87dcea1f4 affected
f4b1363cae43fef7c86c993b7ca7fe7d546b3c68< 65d11eb276836d49003a8060cf31fa2284ad1047 affected
f4b1363cae43fef7c86c993b7ca7fe7d546b3c68< 41fd1e94066a815a7ab0a7025359e9b40e4b3576 affected
… +13 more rows
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I. Basic Information for CVE-2024-49867

Vulnerability Information
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Vulnerability Title
btrfs: wait for fixup workers before stopping cleaner kthread during umount
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: wait for fixup workers before stopping cleaner kthread during umount During unmount, at close_ctree(), we have the following steps in this order: 1) Park the cleaner kthread - this doesn't destroy the kthread, it basically halts its execution (wake ups against it work but do nothing); 2) We stop the cleaner kthread - this results in freeing the respective struct task_struct; 3) We call btrfs_stop_all_workers() which waits for any jobs running in all the work queues and then free the work queues. Syzbot reported a case where a fixup worker resulted in a crash when doing a delayed iput on its inode while attempting to wake up the cleaner at btrfs_add_delayed_iput(), because the task_struct of the cleaner kthread was already freed. This can happen during unmount because we don't wait for any fixup workers still running before we call kthread_stop() against the cleaner kthread, which stops and free all its resources. Fix this by waiting for any fixup workers at close_ctree() before we call kthread_stop() against the cleaner and run pending delayed iputs. The stack traces reported by syzbot were the following: BUG: KASAN: slab-use-after-free in __lock_acquire+0x77/0x2050 kernel/locking/lockdep.c:5065 Read of size 8 at addr ffff8880272a8a18 by task kworker/u8:3/52 CPU: 1 UID: 0 PID: 52 Comm: kworker/u8:3 Not tainted 6.12.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: btrfs-fixup btrfs_work_helper Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 __lock_acquire+0x77/0x2050 kernel/locking/lockdep.c:5065 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162 class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline] try_to_wake_up+0xb0/0x1480 kernel/sched/core.c:4154 btrfs_writepage_fixup_worker+0xc16/0xdf0 fs/btrfs/inode.c:2842 btrfs_work_helper+0x390/0xc50 fs/btrfs/async-thread.c:314 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> Allocated by task 2: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:319 [inline] __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:345 kasan_slab_alloc include/linux/kasan.h:247 [inline] slab_post_alloc_hook mm/slub.c:4086 [inline] slab_alloc_node mm/slub.c:4135 [inline] kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4187 alloc_task_struct_node kernel/fork.c:180 [inline] dup_task_struct+0x57/0x8c0 kernel/fork.c:1107 copy_process+0x5d1/0x3d50 kernel/fork.c:2206 kernel_clone+0x223/0x880 kernel/fork.c:2787 kernel_thread+0x1bc/0x240 kernel/fork.c:2849 create_kthread kernel/kthread.c:412 [inline] kthreadd+0x60d/0x810 kernel/kthread.c:765 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Freed by task 61: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579 poison_slab_object mm/kasan/common.c:247 [inline] __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_h ---truncated---
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于在卸载过程中未等待fixup工作完成就停止cleaner kthread，可能导致使用已释放的cleaner kthread任务结构时发生崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 7a97311de48d56af6db4c5819f95faf9b0b23b1a ~ a71349b692ab34ea197949e13e3cc42570fe73d9 -
Linux Linux 5.6 -

II. Public POCs for CVE-2024-49867

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III. Intelligence Information for CVE-2024-49867

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Patches & Fixes for CVE-2024-49867 (7)

Same Patch Batch · Linux · 2024-10-21 · 372 CVEs total

CVE-2022-48985 9.8 CRITICAL net: mana: Fix race on per-CQ variable napi work_done
CVE-2024-50033 9.8 CRITICAL slip: make slhc_remember() more robust against malicious packets
CVE-2024-49855 9.8 CRITICAL nbd: fix race between timeout and normal completion
CVE-2022-49003 9.8 CRITICAL nvme: fix SRCU protection of nvme_ns_head list
CVE-2024-50043 9.8 CRITICAL nfsd: fix possible badness in FREE_STATEID
CVE-2024-47695 9.8 CRITICAL RDMA/rtrs-clt: Reset cid to con_num - 1 to stay in bounds
CVE-2024-50047 9.8 CRITICAL smb: client: fix UAF in async decryption
CVE-2024-50046 9.8 CRITICAL NFSv4: Prevent NULL-pointer dereference in nfs42_complete_copies()
CVE-2024-49996 9.4 CRITICAL cifs: Fix buffer overflow when parsing NFS reparse points
CVE-2024-47678 9.4 CRITICAL icmp: change the order of rate limits
CVE-2022-49017 8.8 HIGH tipc: re-fetch skb cb after tipc_msg_validate
CVE-2022-49015 8.8 HIGH net: hsr: Fix potential use-after-free
CVE-2024-49950 8.8 HIGH Bluetooth: L2CAP: Fix uaf in l2cap_connect
CVE-2024-49939 8.8 HIGH wifi: rtw89: avoid to add interface to list twice when SER
CVE-2024-50041 8.8 HIGH i40e: Fix macvlan leak by synchronizing access to mac_filter_hash
CVE-2024-49936 8.8 HIGH net/xen-netback: prevent UAF in xenvif_flush_hash()
CVE-2024-50029 8.8 HIGH Bluetooth: hci_conn: Fix UAF in hci_enhanced_setup_sync
CVE-2024-49930 8.8 HIGH wifi: ath11k: fix array out-of-bound access in SoC stats
CVE-2024-49988 8.8 HIGH ksmbd: add refcnt to ksmbd_conn struct
CVE-2024-49982 8.8 HIGH aoe: fix the potential use-after-free problem in more places

Showing top 20 of 372 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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