Linux: Use After Free
CVE-2024-41051 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 ec9289369259d982e735a71437e32e6b4035290c, d3179bae72b1b5e555ba839d6d9f40a350a4d78a, b26525b2183632f16a3a4108fe6a4bfa8afac6ed 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 0.27% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to ec9289369259d982e735a71437e32e6b4035290c or d3179bae72b1b5e555ba839d6d9f40a350a4d78a or b26525b2183632f16a3a4108fe6a4bfa8afac6ed or 12e009d60852f7bce0afc373ca0b320f14150418, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.100 or 6.6.41 or 6.9.10, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | f17443d52d805c9a7fab5e67a4e8b973626fe1cd up to, but not including, ec9289369259d982e735a71437e32e6b4035290c; f740fd943bb1fbf79b7eaba3c71eb7536f437f51 up to, but not including, d3179bae72b1b5e555ba839d6d9f40a350a4d78a; 0a7e54c1959c0feb2de23397ec09c7692364313e up to, but not including, b26525b2183632f16a3a4108fe6a4bfa8afac6ed; 0a7e54c1959c0feb2de23397ec09c7692364313e up to, but not including, 12e009d60852f7bce0afc373ca0b320f14150418; 6.1.95 up to, but not including, 6.1.100; 6.6.35 up to, but not including, 6.6.41; 6.8 | ec9289369259d982e735a71437e32e6b4035290c, d3179bae72b1b5e555ba839d6d9f40a350a4d78a, b26525b2183632f16a3a4108fe6a4bfa8afac6ed, 12e009d60852f7bce0afc373ca0b320f14150418, 6.1.100, 6.6.41 |
| Linux | Linux Kernel | 6.1.95 up to, but not including, 6.1.100; 6.6.35 up to, but not including, 6.6.41; 6.8 up to, but not including, 6.9.10; 6.10 | 6.1.100, 6.6.41, 6.9.10 |
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 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: cachefiles: wait for ondemand_object_worker to finish when dropping object When queuing ondemand_object_worker() to re-open the object, cachefiles_object is not pinned. The cachefiles_object may be freed when the pending read request is completed intentionally and the related erofs is umounted. If ondemand_object_worker() runs after the object is freed, it will incur use-after-free problem as shown below. process A processs B process C process D cachefiles_ondemand_send_req() // send a read req X // wait for its completion // close ondemand fd cachefiles_ondemand_fd_release() // set object as CLOSE cachefiles_ondemand_daemon_read() // set object as REOPENING queue_work(fscache_wq, &info->ondemand_work) // close /dev/cachefiles cachefiles_daemon_release cachefiles_flush_reqs complete(&req->done) // read req X is completed // umount the erofs fs cachefiles_put_object() // object will be freed cachefiles_ondemand_deinit_obj_info() kmem_cache_free(object) // both info and object are freed ondemand_object_worker() When dropping an object, it is no longer necessary to reopen the object, so use cancel_work_sync() to cancel or wait for ondemand_object_worker() to finish.
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
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