audit: fix recursive locking deadlock in audit_dupe_exe()
Why It Matters
Analysis dossierWhy It Matters
In the Linux kernel, the following vulnerability has been resolved: audit: fix recursive locking deadlock in audit_dupe_exe() A deadlock occurs in the audit subsystem when duplicating executable-related rules. When a file is moved (e.g., via do_renameat2()), the VFS layer locks the parent directory (I_MUTEX_PARENT), which synchronously triggers an fsnotify_move event. If an existing executable audit rule matches the file being moved, the audit subsystem catches this event and calls audit_dupe_exe() to duplicate the watch and update the rule. Then, audit_alloc_mark() would call kern_path_parent() to resolve the path, leading to a blind attempt to acquire the exact same I_MUTEX_PARENT lock already held by the task, resulting in the following recursive locking deadlock: ============================================ WARNING: possible recursive locking detected 6.12.0-55.27.1.el10_0.x86_64+debug #1 Not tainted -------------------------------------------- mv/5099 is trying to acquire lock: ffff888132845358 (&inode->i_sb->s_type->i_mutex_dir_key/1){+.+.}-{3:3}, at: __kern_path_locked+0x10a/0x2f0 but task is already holding lock: ffff888132846b58 (&inode->i_sb->s_type->i_mutex_dir_key/1){+.+.}-{3:3}, at: lock_two_directories+0x13f/0x2b0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&inode->i_sb->s_type->i_mutex_dir_key/1); lock(&inode->i_sb->s_type->i_mutex_dir_key/1); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by mv/5099: #0: ffff888112a9c440 (sb_writers#13) at: do_renameat2+0x34c/0xbc0 #1: ffff888112a9c790 (&type->s_vfs_rename_key#3) at: do_renameat2+0x415/0xbc0 #2: ffff888132846b58 (&inode->i_sb->s_type->i_mutex_dir_key/1) at: lock_two_directories+0x13f/0x2b0 #3: ffff888132845358 (&inode->i_sb->s_type->i_mutex_dir_key/5) at: lock_two_directories+0x175/0x2b0 #4: ffffffffb3a1fb10 (&fsnotify_mark_srcu) at: fsnotify+0x454/0x28a0 #5: ffffffffaf886230 (audit_filter_mutex) at: audit_update_watch+0x36/0x11e0 stack backtrace: Call Trace: dump_stack_lvl+0x6f/0xb0 print_deadlock_bug.cold+0xbd/0xca validate_chain+0x83a/0xf00 __lock_acquire+0xcac/0x1d20 lock_acquire.part.0+0x11b/0x360 down_write_nested+0x9f/0x230 __kern_path_locked+0x10a/0x2f0 kern_path_locked+0x26/0x40 audit_alloc_mark+0xfb/0x4f0 audit_dupe_exe+0x6c/0xe0 audit_dupe_rule+0x6c2/0xc00 audit_update_watch+0x4cc/0x11e0 audit_watch_handle_event+0x12c/0x1b0 send_to_group+0x5d0/0x8b0 fsnotify+0x615/0x28a0 fsnotify_move+0x1d8/0x630 vfs_rename+0xdcd/0x1df0 do_renameat2+0x9d4/0xbc0 __x64_sys_renameat+0x192/0x260 do_syscall_64+0x92/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f0491fe8c4e Code: 0f 1f 40 00 48 8b 15 c1 e1 16 00 f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 49 89 ca b8 08 01 00 00 0f 05 <48> 3d 00 f0 ff ff 77 0a c3 66 0f 1f 84 00 00 00 00 00 48 8b 15 89 RSP: 002b:00007ffc7210bf38 EFLAGS: 00000246 ORIG_RAX: 0000000000000108 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0491fe8c4e RDX: 0000000000000003 RSI: 00007ffc7210e6c8 RDI: 00000000ffffff9c RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001 R10: 00005575eb2dae2a R11: 0000000000000246 R12: 00005575eb2dae2a R13: 00007ffc7210e6c8 R14: 0000000000000003 R15: 00000000ffffff9c The aforementioned deadlock can be consistently reproduced by running the script below: audit-dupe-exe-deadlock.sh -------------------------- #!/bin/bash auditctl -D mkdir -p /tmp/foo touch /tmp/file auditctl -a always,exit -F exe=/tmp/file -F path=/tmp/file -S all -k dr mv /tmp/file /tmp/foo/file rm -Rf /tmp/foo This patch fixes the issue by introducing struct audit_watch_ctx to pass the fsnotify event context down to audit_alloc_mark(). By utilizing the already-resolved directory inode provided by the event, we bypass the kern_path_parent() path resol ---truncated---
High
Unknown
Unknown
Risk basis: SOC ecosystem technology relevance; HIGH severity; No confirmed exploitation signal in current enrichment
Affected Products & Remediation
1 source-backed product- azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 · version range not provided by source · Microsoft MSRC · Source
Vendor or catalog guidance (source)
- Microsoft MSRC: CBL-Mariner Releases
Known exploitation (source facts)
Only what a source states. Unknown means no source has said either way; it is not "not exploited".
- CISA KEV
- Unknown
- Exploited (source statement)
- Unknown
- Publicly disclosed (source)
- Unknown
Suggested hunting (rule-based inference)
SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.
Matched local-privilege-escalation (CVSS AV:L, CVSS PR:L)
Exposure
- Identify hosts reporting this CVE, prioritising shared or multi-user systems.Telemetry: DeviceTvmSoftwareVulnerabilities · A local, low-privilege vector matters most where untrusted users can run code. · Rule local-privilege-escalation
Exploitation evidence
- Look for low-privileged processes spawning SYSTEM or root-level child processes on affected hosts.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; privilege transitions are a focused starting point, not evidence of attack. · Rule local-privilege-escalation
Response
- Confirm the source-stated update on affected hosts.Telemetry: DeviceTvmSoftwareVulnerabilities · Host inventory can verify remediation. · Rule local-privilege-escalation
CISA KEV Record
CISA KEV status was not determined for this record.
Change History & Source Data
— No recorded material change
- CNA / source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
- Record status · verification
- UPDATED · NVD API
- CPE
- Unknown
Evidence & Provenance
Linked by the query's stored exact CVE association. Review required tables and validation status before use.
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-68096"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc