Linux Kernel up to 5.18.2 dlmfs fs/ocfs2/dlmfs/userdlm.c user_dlm_destroy_lock use after free

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 5.18.2. Affected is the function user_dlm_destroy_lock of the file fs/ocfs2/dlmfs/userdlm.c of the component dlmfs. The manipulation results in use after free. This vulnerability is identified as CVE-2022-49337. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 5.18.2. Affected is the function user_dlm_destroy_lock of the file fs/ocfs2/dlmfs/userdlm.c of the component dlmfs. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ocfs2: dlmfs: fix error handling of user_dlm_destroy_lock When user_dlm_destroy_lock failed, it didn't clean up the flags it set before exit. For USER_LOCK_IN_TEARDOWN, if this function fails because of lock is still in used, next time when unlink invokes this function, it will return succeed, and then unlink will remove inode and dentry if lock is not in used(file closed), but the dlm lock is still linked in dlm lock resource, then when bast come in, it will trigger a panic due to user-after-free. See the following panic call trace. To fix this, USER_LOCK_IN_TEARDOWN should be reverted if fail. And also error should be returned if USER_LOCK_IN_TEARDOWN is set to let user know that unlink fail. For the case of ocfs2_dlm_unlock failure, besides USER_LOCK_IN_TEARDOWN, USER_LOCK_BUSY is also required to be cleared. Even though spin lock is released in between, but USER_LOCK_IN_TEARDOWN is still set, for USER_LOCK_BUSY, if before every place that waits on this flag, USER_LOCK_IN_TEARDOWN is checked to bail out, that will make sure no flow waits on the busy flag set by user_dlm_destroy_lock(), then we can simplely revert USER_LOCK_BUSY when ocfs2_dlm_unlock fails. Fix user_dlm_cluster_lock() which is the only function not following this. [ 941.336392] (python,26174,16):dlmfs_unlink:562 ERROR: unlink 004fb0000060000b5a90b8c847b72e1, error -16 from destroy [ 989.757536] ------------[ cut here ]------------ [ 989.757709] kernel BUG at fs/ocfs2/dlmfs/userdlm.c:173! [ 989.757876] invalid opcode: 0000 [#1] SMP [ 989.758027] Modules linked in: ksplice_2zhuk2jr_ib_ipoib_new(O) ksplice_2zhuk2jr(O) mptctl mptbase xen_netback xen_blkback xen_gntalloc xen_gntdev xen_evtchn cdc_ether usbnet mii ocfs2 jbd2 rpcsec_gss_krb5 auth_rpcgss nfsv4 nfsv3 nfs_acl nfs fscache lockd grace ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager ocfs2_stackglue configfs bnx2fc fcoe libfcoe libfc scsi_transport_fc sunrpc ipmi_devintf bridge stp llc rds_rdma rds bonding ib_sdp ib_ipoib rdma_ucm ib_ucm ib_uverbs ib_umad rdma_cm ib_cm iw_cm falcon_lsm_serviceable(PE) falcon_nf_netcontain(PE) mlx4_vnic falcon_kal(E) falcon_lsm_pinned_13402(E) mlx4_ib ib_sa ib_mad ib_core ib_addr xenfs xen_privcmd dm_multipath iTCO_wdt iTCO_vendor_support pcspkr sb_edac edac_core i2c_i801 lpc_ich mfd_core ipmi_ssif i2c_core ipmi_si ipmi_msghandler [ 989.760686] ioatdma sg ext3 jbd mbcache sd_mod ahci libahci ixgbe dca ptp pps_core vxlan udp_tunnel ip6_udp_tunnel megaraid_sas mlx4_core crc32c_intel be2iscsi bnx2i cnic uio cxgb4i cxgb4 cxgb3i libcxgbi ipv6 cxgb3 mdio libiscsi_tcp qla4xxx iscsi_boot_sysfs libiscsi scsi_transport_iscsi wmi dm_mirror dm_region_hash dm_log dm_mod [last unloaded: ksplice_2zhuk2jr_ib_ipoib_old] [ 989.761987] CPU: 10 PID: 19102 Comm: dlm_thread Tainted: P OE 4.1.12-124.57.1.el6uek.x86_64 #2 [ 989.762290] Hardware name: Oracle Corporation ORACLE SERVER X5-2/ASM,MOTHERBOARD,1U, BIOS 30350100 06/17/2021 [ 989.762599] task: ffff880178af6200 ti: ffff88017f7c8000 task.ti: ffff88017f7c8000 [ 989.762848] RIP: e030:[] [] __user_dlm_queue_lockres.part.4+0x76/0x80 [ocfs2_dlmfs] [ 989.763185] RSP: e02b:ffff88017f7cbcb8 EFLAGS: 00010246 [ 989.763353] RAX: 0000000000000000 RBX: ffff880174d48008 RCX: 0000000000000003 [ 989.763565] RDX: 0000000000120012 RSI: 0000000000000003 RDI: ffff880174d48170 [ 989.763778] RBP: ffff88017f7cbcc8 R08: ffff88021f4293b0 R09: 0000000000000000 [ 989.763991] R10: ffff880179c8c000 R11: 0000000000000003 R12: ffff880174d48008 [ 989.764204] R13: 0000000000000003 R14: ffff880179c8c000 R15: ffff88021db7a000 [ 989.764422] FS: 0000000000000000(0000) GS:ffff880247480000(0000) knlGS:ffff880247480000 [ 989.764685] CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 989.764865] CR2: ffff8000007f6800 CR3: 0000000001ae0000 CR4: 0000000000042660 [ 989.765081] Stack: [ 989.765167] 00000000000 ---truncated---

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2022-49337 since 02/26/2025. The exploitability is told to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 02/16/2026).

Upgrading to version 4.9.318, 4.14.283, 4.19.247, 5.4.198, 5.10.121, 5.15.46, 5.17.14 or 5.18.3 eliminates this vulnerability. Applying the patch 1434cd71ad9f3a6beda3036972983b6c4869207c/733a35c00ef363a1c774d7ea486e0735b7c13a15/82bf8e7271fade40184177cb406203addc34c4a0/337e36550788dbe03254f0593a231c1c4873b20d/9c96238fac045b289993d7bc5aae7b2d72b25c76/efb54ec548829e1d3605f0434526f86e345b1b28/2c5e26a626fe46675bceba853e12aaf13c712e10/863e0d81b6683c4cbc588ad831f560c90e494bef is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2025-2107). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Open Source Linux Kernel
• RESF Rocky Linux
• Dell Secure Connect Gateway
• IBM QRadar SIEM
• Dell NetWorker

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 4.9.317
• 4.14.282
• 4.19.246
• 5.4.197
• 5.10.120
• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4
• 5.15.5
• 5.15.6
• 5.15.7
• 5.15.8
• 5.15.9
• 5.15.10
• 5.15.11
• 5.15.12
• 5.15.13
• 5.15.14
• 5.15.15
• 5.15.16
• 5.15.17
• 5.15.18
• 5.15.19
• 5.15.20
• 5.15.21
• 5.15.22
• 5.15.23
• 5.15.24
• 5.15.25
• 5.15.26
• 5.15.27
• 5.15.28
• 5.15.29
• 5.15.30
• 5.15.31
• 5.15.32
• 5.15.33
• 5.15.34
• 5.15.35
• 5.15.36
• 5.15.37
• 5.15.38
• 5.15.39
• 5.15.40
• 5.15.41
• 5.15.42
• 5.15.43
• 5.15.44
• 5.15.45
• 5.17.0
• 5.17.1
• 5.17.2
• 5.17.3
• 5.17.4
• 5.17.5
• 5.17.6
• 5.17.7
• 5.17.8
• 5.17.9
• 5.17.10
• 5.17.11
• 5.17.12
• 5.17.13
• 5.18.0
• 5.18.1
• 5.18.2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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