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CVE-2021-46972— ovl: fix leaked dentry

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，该漏洞源于当存在临时目录项时，overlayfs 不会放置临时目录项 元复制错误，导致关闭相关超级块时导致 dentry 泄漏。

AI Predicted 4.3 Difficulty: Easy EPSS 0.25% · P15

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 6815f479ca90ee7fd2e28b2a420f796b974155fe< 71d58457a8afc650da5d3292a7f7029317654d95 affected
6815f479ca90ee7fd2e28b2a420f796b974155fe< cf3e3330bc5719fa9d658e3e2f596bde89344a94 affected
6815f479ca90ee7fd2e28b2a420f796b974155fe< d587cfaef72b1b6f4b2774827123bce91f497cc8 affected
6815f479ca90ee7fd2e28b2a420f796b974155fe< eaab1d45cdb4bb0c846bd23c3d666d5b90af7b41 affected
5.8 affected
< 5.8 unaffected
5.10.35≤ 5.10.* unaffected
5.11.19≤ 5.11.* unaffected
… +2 more rows
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I. Basic Information for CVE-2021-46972

Vulnerability Information
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Vulnerability Title
ovl: fix leaked dentry
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ovl: fix leaked dentry Since commit 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a metacopy error, which leads to dentry leaks when shutting down the related superblock: overlayfs: refusing to follow metacopy origin for (/file0) ... BUG: Dentry (____ptrval____){i=3f33,n=file3} still in use (1) [unmount of overlay overlay] ... WARNING: CPU: 1 PID: 432 at umount_check.cold+0x107/0x14d CPU: 1 PID: 432 Comm: unmount-overlay Not tainted 5.12.0-rc5 #1 ... RIP: 0010:umount_check.cold+0x107/0x14d ... Call Trace: d_walk+0x28c/0x950 ? dentry_lru_isolate+0x2b0/0x2b0 ? __kasan_slab_free+0x12/0x20 do_one_tree+0x33/0x60 shrink_dcache_for_umount+0x78/0x1d0 generic_shutdown_super+0x70/0x440 kill_anon_super+0x3e/0x70 deactivate_locked_super+0xc4/0x160 deactivate_super+0xfa/0x140 cleanup_mnt+0x22e/0x370 __cleanup_mnt+0x1a/0x30 task_work_run+0x139/0x210 do_exit+0xb0c/0x2820 ? __kasan_check_read+0x1d/0x30 ? find_held_lock+0x35/0x160 ? lock_release+0x1b6/0x660 ? mm_update_next_owner+0xa20/0xa20 ? reacquire_held_locks+0x3f0/0x3f0 ? __sanitizer_cov_trace_const_cmp4+0x22/0x30 do_group_exit+0x135/0x380 __do_sys_exit_group.isra.0+0x20/0x20 __x64_sys_exit_group+0x3c/0x50 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xae ... VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds. Have a nice day... This fix has been tested with a syzkaller reproducer.
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，该漏洞源于当存在临时目录项时，overlayfs 不会放置临时目录项 元复制错误，导致关闭相关超级块时导致 dentry 泄漏。
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 6815f479ca90ee7fd2e28b2a420f796b974155fe ~ 71d58457a8afc650da5d3292a7f7029317654d95 -
Linux Linux 5.8 -

II. Public POCs for CVE-2021-46972

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III. Intelligence Information for CVE-2021-46972

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Other References for CVE-2021-46972 (4)

Same Patch Batch · Linux · 2024-02-27 · 67 CVEs total

CVE-2021-46911 9.8 CRITICAL ch_ktls: Fix kernel panic
CVE-2021-46955 8.2 HIGH openvswitch: fix stack OOB read while fragmenting IPv4 packets
CVE-2021-46936 7.8 HIGH net: fix use-after-free in tw_timer_handler
CVE-2021-46913 7.8 HIGH netfilter: nftables: clone set element expression template
CVE-2021-46973 7.8 HIGH net: qrtr: Avoid potential use after free in MHI send
CVE-2021-46969 7.8 HIGH bus: mhi: core: Fix invalid error returning in mhi_queue
CVE-2021-46967 7.8 HIGH vhost-vdpa: fix vm_flags for virtqueue doorbell mapping
CVE-2021-46921 7.8 HIGH locking/qrwlock: Fix ordering in queued_write_lock_slowpath()
CVE-2021-46925 7.8 HIGH net/smc: fix kernel panic caused by race of smc_sock
CVE-2021-46963 7.8 HIGH scsi: qla2xxx: Fix crash in qla2xxx_mqueuecommand()
CVE-2021-46929 7.8 HIGH sctp: use call_rcu to free endpoint
CVE-2021-46958 7.8 HIGH btrfs: fix race between transaction aborts and fsyncs leading to use-after-free
CVE-2021-46933 7.8 HIGH usb: gadget: f_fs: Clear ffs_eventfd in ffs_data_clear.
CVE-2021-46922 7.8 HIGH KEYS: trusted: Fix TPM reservation for seal/unseal
CVE-2021-46960 7.5 HIGH cifs: Return correct error code from smb2_get_enc_key
CVE-2021-46948 7.5 HIGH sfc: farch: fix TX queue lookup in TX event handling
CVE-2021-46912 7.3 HIGH net: Make tcp_allowed_congestion_control readonly in non-init netns
CVE-2021-46974 7.1 HIGH bpf: Fix masking negation logic upon negative dst register
CVE-2021-46908 7.1 HIGH bpf: Use correct permission flag for mixed signed bounds arithmetic
CVE-2021-46910 7.0 HIGH ARM: 9063/1: mm: reduce maximum number of CPUs if DEBUG_KMAP_LOCAL is enabled

Showing top 20 of 67 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-46972

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