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Linux KernelOperating system · Linux

CVE-2022-49337

MEDIUM · 5.5 CVSS v3.1 Published 2025-02-26
Fix available
A fix is available. Upgrade to 4.9.318 / 4.14.283 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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:[<ffffffffc07d4316>] [<ffffffffc07d4316>] __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---

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-667

Shared resources are accessed without correct locking, so concurrent operations interleave into inconsistent — and sometimes exploitable — states, or deadlock the service outright. These bugs are subtle and timing-dependent. The fix is correct, consistent locking or atomic operations around every shared resource.

General guidance for the improper locking class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:< 4.9.318>= 4.10, < 4.14.283>= 4.15, < 4.19.247>= 4.20, < 5.4.198>= 5.5, < 5.10.121>= 5.11, < 5.15.46>= 5.16, < 5.17.14>= 5.18, < 5.18.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.9.318 / 4.14.283 / 4.19.247 or later
Fixed in 4.9.3184.14.2834.19.247
Vendor patch git.kernel.org →
Recommended fix High confidence

5.4.198 or later (or 4.19.247+, 4.14.283+, or 4.9.318+ depending on desired branch)

  1. Identify current kernel version using `uname -r`
  2. Download and install a kernel version >= 5.4.198, or >= 4.19.247 if staying in the 4.19.y branch, or >= 4.14.283 if staying in the 4.14.y branch, or >= 4.9.318 if staying in the 4.9.y branch
  3. Reboot the system into the new kernel using `reboot`
  4. Verify the fix is applied by checking the kernel version with `uname -r` and confirming the patch is present in `/usr/src/linux/fs/ocfs2/dlmfs/userdlm.c`
Caveat Upgrading kernel may require matching system utilities and could introduce regressions in other drivers; test in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

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Peer-ranked notes from engineers who’ve handled CVE-2022-49337 in production — separate from our analysis above.

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