Read the docs
TI-2026-81911 Aliases CVE-2026-99204GHSA-h9q4-gj29-45hp

Use-after-free in Linux kernel OCFS2 DLM debugfs state reads

Priority LOW 22Published · Updated

Key facts

Attack vector
—
Privileges required
—
User interaction
—
Attack complexity
—
Impact type
—
Confidentiality · integrity · availability
—
Fix status
Partial Red Hat: 1 without a fix

No CVSS vector from any source. Fix status from CNA and Red Hat.

Summary

The Linux kernel OCFS2 distributed lock manager (ocfs2/dlm) is affected from 2.6.26 before the fixed releases. The debugfs state printer walks the recovery participant list without holding the lock that protects it, so a record can be freed while it is being read. A concurrent debugfs open can therefore read freed kernel memory, which KASAN reports as a slab-use-after-free.

Written with Claude Haiku 5.5 from the sources below · 2026-11-01

Description from the CNA

In the Linux kernel, the following vulnerability has been resolved: ocfs2/dlm: Protect the recovery list during debugfs reads Recovery participant records must remain alive while debug_state_print() walks reco.node_data and formats their fields. The formatter holds dlm->spinlock, but the recovery participant list is protected by dlm_reco_state_lock. In particular, dlm_destroy_recovery_area() detaches the list under dlm_reco_state_lock and frees the detached records after releasing it. A concurrent debugfs open can therefore read freed memory. Protect the participant traversal and field reads in debug_state_print() with dlm_reco_state_lock, matching the existing list writers. This also serializes the traversal against list_add_tail() during recovery-area initialization. Make the existing lock available to the debug code through dlmcommon.h; the lock remains internal to the OCFS2 DLM module. Release dlm->spinlock after formatting the other domain state and before acquiring dlm_reco_state_lock, so the debug reader does not nest the two locks. Leave recovery list insertion, detachment and freeing unchanged. KASAN report as below: BUG: KASAN: slab-use-after-free in debug_state_open+0x1169/0x12d0 Read of size 4 at addr ffff88810662ef80 by task dlm-state-stres/896 CPU: 1 UID: 0 PID: 896 Comm: dlm-state-stres Not tainted 7.3.0-rc4-next-20260921-pmb-ocfs2-functional-v1+ #1 PREEMPT(lazy) Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x93/0xd0 print_report+0xce/0x630 ? debug_state_open+0x1169/0x12d0 ? srso_alias_return_thunk+0x5/0xfbef5 ? __virt_addr_valid+0x20e/0x420 ? debug_state_open+0x1169/0x12d0 kasan_report+0xe0/0x110 ? debug_state_open+0x1169/0x12d0 debug_state_open+0x1169/0x12d0 ? __pfx_debug_state_open+0x10/0x10 full_proxy_open_regular+0x193/0x310 do_dentry_open+0x595/0x12d0 ? __pfx_full_proxy_open_regular+0x10/0x10 vfs_open_consume+0xd1/0x400 ? srso_alias_return_thunk+0x5/0xfbef5 path_openat+0x18d0/0x2020 ? __pfx_path_openat+0x10/0x10 do_file_open+0x21e/0x470 ? __pfx_do_file_open+0x10/0x10 ? _raw_spin_unlock+0x23/0x40 ? srso_alias_return_thunk+0x5/0xfbef5 ? alloc_fd+0x3a6/0x6b0 do_sys_openat2+0xf4/0x1b0 ? __pfx_do_sys_openat2+0x10/0x10 ? srso_alias_return_thunk+0x5/0xfbef5 ? __fput+0x5b5/0xa60 __x64_sys_openat+0x136/0x1e0 ? __pfx___x64_sys_openat+0x10/0x10 do_syscall_64+0x114/0x620 entry_SYSCALL_64_after_hwframe+0x77/0x7f [Register dump omitted.] </TASK> Allocated by task 880: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0xaa/0xb0 __kmalloc_cache_noprof+0x28d/0x610 dlm_remaster_locks+0x147/0x1d90 dlm_do_recovery+0xde1/0x1580 dlm_recovery_thread+0x109/0x300 kthread+0x351/0x460 ret_from_fork+0x659/0x940 ret_from_fork_asm+0x1a/0x30 Freed by task 880: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x5f/0x80 kfree+0x308/0x580 dlm_destroy_recovery_area+0x285/0x460 dlm_remaster_locks+0x17c4/0x1d90 dlm_do_recovery+0xde1/0x1580 dlm_recovery_thread+0x109/0x300 kthread+0x351/0x460 ret_from_fork+0x659/0x940 ret_from_fork_asm+0x1a/0x30 The buggy address belongs to the object at ffff88810662ef80 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes inside of freed 32-byte region [ffff88810662ef80, ffff88810662efa0) [Page and memory-state dumps omitted.]

Why it matters now

EPSS 0.00171 6th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.10.273, 5.15.224, 6.1.191 +5Red Hat: 1 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux2.6.26 and later5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3Patch availableCNA
  • Linux VendorLinux Affected 2.6.26 and later Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*——Linux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

Upgrade the Linux kernel to 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13 or 7.3, depending on the release branch in use. Red Hat has no fix available for Red Hat OpenShift Container Platform 5, which it lists as affected.

Written with Claude Haiku 5.5 from the sources below · 2026-11-01

  • Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.59, 7.2.13, 7.3

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat OpenShift Container Platform 5AffectedNo fix yet: Fix deferred
Not affected: 6 products
  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat OpenShift Container Platform 4

Timeline

  1. 2026-10-28 Threatist record created from CVE-2026-99204
  2. 2026-10-28 Alias added: GHSA-h9q4-gj29-45hp
  3. 2026-10-29 Affected versions changed · Red Hat
  4. 2026-10-29 CVSS score added · Red Hat
  5. 2026-10-30 Fix available: Linux/Linux@03f2fdcc94238a5127ff8a21a4544fd6118cfc7b, Linux/Linux@1c1dbaa16d70cf3d6b9b21503fc188f560376866, Linux/Linux@25de9d3b5a81ba7bd52fdc9601f9ea7d1d3d6ae8 +7 · CNA
  6. 2026-10-30 5 new references · CNA
  7. 2026-11-01 Affected versions changed · Red Hat

References

Other 8

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
See all 21741 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences