Host crash via IMA RCU use-after-free
Published Jul 12, 2024 · Updated Aug 5, 2026
Use-after-free in the Linux kernel IMA subsystem allows local users to crash the host during concurrent security-policy updates. ima_lsm_copy_rule allocates with GFP_KERNEL inside ima_match_policy's RCU read-side critical section, so a sleep can let synchronize_rcu return before the reader finishes and expose a freed rule entry. The race requires ordinary local file opens, memory pressure, a non-PREEMPT kernel, and a concurrent administrator-triggered LSM policy update; the demonstrated consequence is a kernel panic.
Summary
What happened
Use-after-free in the Linux kernel IMA subsystem allows local users to crash the host during concurrent security-policy updates. ima_lsm_copy_rule allocates with GFP_KERNEL inside ima_match_policy's RCU read-side critical section, so a sleep can let synchronize_rcu return before the reader finishes and expose a freed rule entry. The race requires ordinary local file opens, memory pressure, a non-PREEMPT kernel, and a concurrent administrator-triggered LSM policy update; the demonstrated consequence is a kernel panic.
The record
- CVE
- CVE-2024-40947
- Published
- Jul 12, 2024
- Updated
- Aug 5, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-476, T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 12, 2024CVE publishedPublication date reported by the CVE source.
- Aug 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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- Affected versionversion=2d4bc60693c4206c64723e94ae5f7a04c0b8f18f <a38e02265c681b51997a264aaf743095e2ee400a
- Affected versionversion=38d48fd224036717fcb3437e7af1314f6ebcd2d0
- Affected versionversion=5.10.163 <5.10.222
- Affected versionversion=5.15.86 <5.15.163
- Affected versionversion=5.4.229 <5.5
- Affected versionversion=6.0.16 <6.1
- Affected versionversion=6.1.2 <6.1.98
- Affected versionversion=6.2
- Affected versionversion=69c60b2a2dbb4887739d3a13297cc0dae3793f35
- Affected versionversion=8008f1691c15f353f5a53dc5d450b8262cb57421 <9c3906c3738562b1fedc6f1cfc81756a7cfefff0
- Affected versionversion=c4b035b1f036ddd53fbfced49046e586c5ad8a3e <a6176a802c4bfb83bf7524591aa75f44a639a853
- Affected versionversion=c7423dbdbc9ecef7fff5239d144cad4b9887f4de <28d0ecc52f6c927d0e9ba70a4f2c1ea15453ee88
- Affected versionversion=c7423dbdbc9ecef7fff5239d144cad4b9887f4de <58275455893066149e9f4df2223ab2fdbdc59f9c
- Affected versionversion=c7423dbdbc9ecef7fff5239d144cad4b9887f4de <9a95c5bfbf02a0a7f5983280fe284a0ff0836c34
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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