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CVE-2022-49702— btrfs: fix hang during unmount when block group reclaim task is running

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btrfs在卸载时与块组回收任务发生死锁。

AI Predicted 5.5 Difficulty: Trivial EPSS 0.21% · P10

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 18bb8bbf13c1839b43c9e09e76d397b753989af2< 341d33128a940c6634175dcb6ca92dc454cfa7d2 affected
18bb8bbf13c1839b43c9e09e76d397b753989af2< 9fadb11f1295289e0da4d3342ecb6b92c1c99540 affected
18bb8bbf13c1839b43c9e09e76d397b753989af2< 31e70e527806c546a72262f2fc3d982ee23c42d3 affected
5.13 affected
< 5.13 unaffected
5.15.51≤ 5.15.* unaffected
5.18.8≤ 5.18.* unaffected
5.19≤ * unaffected
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I. Basic Information for CVE-2022-49702

Vulnerability Information
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Vulnerability Title
btrfs: fix hang during unmount when block group reclaim task is running
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix hang during unmount when block group reclaim task is running When we start an unmount, at close_ctree(), if we have the reclaim task running and in the middle of a data block group relocation, we can trigger a deadlock when stopping an async reclaim task, producing a trace like the following: [629724.498185] task:kworker/u16:7 state:D stack: 0 pid:681170 ppid: 2 flags:0x00004000 [629724.499760] Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs] [629724.501267] Call Trace: [629724.501759] <TASK> [629724.502174] __schedule+0x3cb/0xed0 [629724.502842] schedule+0x4e/0xb0 [629724.503447] btrfs_wait_on_delayed_iputs+0x7c/0xc0 [btrfs] [629724.504534] ? prepare_to_wait_exclusive+0xc0/0xc0 [629724.505442] flush_space+0x423/0x630 [btrfs] [629724.506296] ? rcu_read_unlock_trace_special+0x20/0x50 [629724.507259] ? lock_release+0x220/0x4a0 [629724.507932] ? btrfs_get_alloc_profile+0xb3/0x290 [btrfs] [629724.508940] ? do_raw_spin_unlock+0x4b/0xa0 [629724.509688] btrfs_async_reclaim_metadata_space+0x139/0x320 [btrfs] [629724.510922] process_one_work+0x252/0x5a0 [629724.511694] ? process_one_work+0x5a0/0x5a0 [629724.512508] worker_thread+0x52/0x3b0 [629724.513220] ? process_one_work+0x5a0/0x5a0 [629724.514021] kthread+0xf2/0x120 [629724.514627] ? kthread_complete_and_exit+0x20/0x20 [629724.515526] ret_from_fork+0x22/0x30 [629724.516236] </TASK> [629724.516694] task:umount state:D stack: 0 pid:719055 ppid:695412 flags:0x00004000 [629724.518269] Call Trace: [629724.518746] <TASK> [629724.519160] __schedule+0x3cb/0xed0 [629724.519835] schedule+0x4e/0xb0 [629724.520467] schedule_timeout+0xed/0x130 [629724.521221] ? lock_release+0x220/0x4a0 [629724.521946] ? lock_acquired+0x19c/0x420 [629724.522662] ? trace_hardirqs_on+0x1b/0xe0 [629724.523411] __wait_for_common+0xaf/0x1f0 [629724.524189] ? usleep_range_state+0xb0/0xb0 [629724.524997] __flush_work+0x26d/0x530 [629724.525698] ? flush_workqueue_prep_pwqs+0x140/0x140 [629724.526580] ? lock_acquire+0x1a0/0x310 [629724.527324] __cancel_work_timer+0x137/0x1c0 [629724.528190] close_ctree+0xfd/0x531 [btrfs] [629724.529000] ? evict_inodes+0x166/0x1c0 [629724.529510] generic_shutdown_super+0x74/0x120 [629724.530103] kill_anon_super+0x14/0x30 [629724.530611] btrfs_kill_super+0x12/0x20 [btrfs] [629724.531246] deactivate_locked_super+0x31/0xa0 [629724.531817] cleanup_mnt+0x147/0x1c0 [629724.532319] task_work_run+0x5c/0xa0 [629724.532984] exit_to_user_mode_prepare+0x1a6/0x1b0 [629724.533598] syscall_exit_to_user_mode+0x16/0x40 [629724.534200] do_syscall_64+0x48/0x90 [629724.534667] entry_SYSCALL_64_after_hwframe+0x44/0xae [629724.535318] RIP: 0033:0x7fa2b90437a7 [629724.535804] RSP: 002b:00007ffe0b7e4458 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 [629724.536912] RAX: 0000000000000000 RBX: 00007fa2b9182264 RCX: 00007fa2b90437a7 [629724.538156] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000555d6cf20dd0 [629724.539053] RBP: 0000555d6cf20ba0 R08: 0000000000000000 R09: 00007ffe0b7e3200 [629724.539956] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [629724.540883] R13: 0000555d6cf20dd0 R14: 0000555d6cf20cb0 R15: 0000000000000000 [629724.541796] </TASK> This happens because: 1) Before entering close_ctree() we have the async block group reclaim task running and relocating a data block group; 2) There's an async metadata (or data) space reclaim task running; 3) We enter close_ctree() and park the cleaner kthread; 4) The async space reclaim task is at flush_space() and runs all the existing delayed iputs; 5) Before the async space reclaim task calls btrfs_wait_on_delayed_iputs(), the block group reclaim task which is doing the data block group relocation, creates a delayed iput at replace_file_extents() (called when COWing leaves that have file extent items pointing to relocated data exten ---truncated---
Source: CVE Program / CVE List V5
CVSS Information
N/A
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btrfs在卸载时与块组回收任务发生死锁。
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 18bb8bbf13c1839b43c9e09e76d397b753989af2 ~ 341d33128a940c6634175dcb6ca92dc454cfa7d2 -
Linux Linux 5.13 -

II. Public POCs for CVE-2022-49702

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III. Intelligence Information for CVE-2022-49702

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Patches & Fixes for CVE-2022-49702 (3)

Same Patch Batch · Linux · 2025-02-26 · 706 CVEs total

CVE-2022-49149 9.8 CRITICAL rxrpc: Fix call timer start racing with call destruction
CVE-2022-49561 9.8 CRITICAL netfilter: conntrack: re-fetch conntrack after insertion
CVE-2022-49362 9.8 CRITICAL NFSD: Fix potential use-after-free in nfsd_file_put()
CVE-2022-49201 9.8 CRITICAL ibmvnic: fix race between xmit and reset
CVE-2022-49194 9.8 CRITICAL net: bcmgenet: Use stronger register read/writes to assure ordering
CVE-2022-49093 9.8 CRITICAL skbuff: fix coalescing for page_pool fragment recycling
CVE-2022-49260 9.8 CRITICAL crypto: hisilicon/sec - fix the aead software fallback for engine
CVE-2022-49418 9.8 CRITICAL NFSv4: Fix free of uninitialized nfs4_label on referral lookup.
CVE-2022-49094 9.8 CRITICAL net/tls: fix slab-out-of-bounds bug in decrypt_internal
CVE-2022-49407 9.8 CRITICAL dlm: fix plock invalid read
CVE-2022-49280 9.8 CRITICAL NFSD: prevent underflow in nfssvc_decode_writeargs()
CVE-2022-49356 9.8 CRITICAL SUNRPC: Trap RDMA segment overflows
CVE-2022-49058 9.1 CRITICAL cifs: potential buffer overflow in handling symlinks
CVE-2022-49500 8.8 HIGH wl1251: dynamically allocate memory used for DMA
CVE-2022-49535 8.8 HIGH scsi: lpfc: Fix null pointer dereference after failing to issue FLOGI and PLOGI
CVE-2022-49114 8.8 HIGH scsi: libfc: Fix use after free in fc_exch_abts_resp()
CVE-2022-49470 8.8 HIGH Bluetooth: btmtksdio: fix use-after-free at btmtksdio_recv_event
CVE-2022-49111 8.8 HIGH Bluetooth: Fix use after free in hci_send_acl
CVE-2022-49238 8.8 HIGH ath11k: free peer for station when disconnect from AP for QCA6390/WCN6855
CVE-2022-49519 8.8 HIGH ath10k: skip ath10k_halt during suspend for driver state RESTARTING

Showing top 20 of 706 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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