Linux: Use After Free
CVE-2024-38570 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 94b32a85d1a76ae4f1b42a88677fa20b20187729, 0636b34b44589b142700ac137b5f69802cfe2e37, e42e8a24d7f02d28763d16ca7ec5fc6d1f142af0 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.68% chance of exploitation within 30 days, higher than 53% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 94b32a85d1a76ae4f1b42a88677fa20b20187729 or 0636b34b44589b142700ac137b5f69802cfe2e37 or e42e8a24d7f02d28763d16ca7ec5fc6d1f142af0 or 501cd8fabf621d10bd4893e37f6ce6c20523c8ca, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.33 or 6.8.12 or 6.9.3, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | fb6791d100d1bba20b5cdbc4912e1f7086ec60f8 up to, but not including, 94b32a85d1a76ae4f1b42a88677fa20b20187729; fb6791d100d1bba20b5cdbc4912e1f7086ec60f8 up to, but not including, 0636b34b44589b142700ac137b5f69802cfe2e37; fb6791d100d1bba20b5cdbc4912e1f7086ec60f8 up to, but not including, e42e8a24d7f02d28763d16ca7ec5fc6d1f142af0; fb6791d100d1bba20b5cdbc4912e1f7086ec60f8 up to, but not including, 501cd8fabf621d10bd4893e37f6ce6c20523c8ca; fb6791d100d1bba20b5cdbc4912e1f7086ec60f8 up to, but not including, d98779e687726d8f8860f1c54b5687eec5f63a73; 3.8 | 94b32a85d1a76ae4f1b42a88677fa20b20187729, 0636b34b44589b142700ac137b5f69802cfe2e37, e42e8a24d7f02d28763d16ca7ec5fc6d1f142af0, 501cd8fabf621d10bd4893e37f6ce6c20523c8ca, d98779e687726d8f8860f1c54b5687eec5f63a73 |
| Linux | Linux Kernel | 3.8 up to, but not including, 6.6.33; 6.7 up to, but not including, 6.8.12; 6.9 up to, but not including, 6.9.3 | 6.6.33, 6.8.12, 6.9.3 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix potential glock use-after-free on unmount When a DLM lockspace is released and there ares still locks in that lockspace, DLM will unlock those locks automatically. Commit fb6791d100d1b started exploiting this behavior to speed up filesystem unmount: gfs2 would simply free glocks it didn't want to unlock and then release the lockspace. This didn't take the bast callbacks for asynchronous lock contention notifications into account, which remain active until until a lock is unlocked or its lockspace is released. To prevent those callbacks from accessing deallocated objects, put the glocks that should not be unlocked on the sd_dead_glocks list, release the lockspace, and only then free those glocks. As an additional measure, ignore unexpected ast and bast callbacks if the receiving glock is dead.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Use After Free vulnerabilities
- 7.0 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.0 High severity
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