Linux: Use After Free
CVE-2024-41050 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 35710c6c4a1c64478ec1b5e0e81d386c0844dec6, de045a82e1a4e04be62718d3c2981a55150765a0, 9d3bf4e9aa23f0d9e99ebe7a94f232ddba54ee17 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 0.28% 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 35710c6c4a1c64478ec1b5e0e81d386c0844dec6 or de045a82e1a4e04be62718d3c2981a55150765a0 or 9d3bf4e9aa23f0d9e99ebe7a94f232ddba54ee17 or 19f4f399091478c95947f6bd7ad61622300c30d9, 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 | c8383054506c77b814489c09877b5db83fd4abf2 up to, but not including, 35710c6c4a1c64478ec1b5e0e81d386c0844dec6; c8383054506c77b814489c09877b5db83fd4abf2 up to, but not including, de045a82e1a4e04be62718d3c2981a55150765a0; c8383054506c77b814489c09877b5db83fd4abf2 up to, but not including, 9d3bf4e9aa23f0d9e99ebe7a94f232ddba54ee17; c8383054506c77b814489c09877b5db83fd4abf2 up to, but not including, 19f4f399091478c95947f6bd7ad61622300c30d9; 5.19 | 35710c6c4a1c64478ec1b5e0e81d386c0844dec6, de045a82e1a4e04be62718d3c2981a55150765a0, 9d3bf4e9aa23f0d9e99ebe7a94f232ddba54ee17, 19f4f399091478c95947f6bd7ad61622300c30d9 |
| Linux | Linux Kernel | 5.19 up to, but not including, 6.1.100; 6.2 up to, but not including, 6.6.41; 6.7 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.
Official description
In the Linux kernel, the following vulnerability has been resolved: cachefiles: cyclic allocation of msg_id to avoid reuse Reusing the msg_id after a maliciously completed reopen request may cause a read request to remain unprocessed and result in a hung, as shown below: t1 | t2 | t3 ------------------------------------------------- cachefiles_ondemand_select_req cachefiles_ondemand_object_is_close(A) cachefiles_ondemand_set_object_reopening(A) queue_work(fscache_object_wq, &info->work) ondemand_object_worker cachefiles_ondemand_init_object(A) cachefiles_ondemand_send_req(OPEN) // get msg_id 6 wait_for_completion(&req_A->done) cachefiles_ondemand_daemon_read // read msg_id 6 req_A cachefiles_ondemand_get_fd copy_to_user // Malicious completion msg_id 6 copen 6,-1 cachefiles_ondemand_copen complete(&req_A->done) // will not set the object to close // because ondemand_id && fd is valid. // ondemand_object_worker() is done // but the object is still reopening. // new open req_B cachefiles_ondemand_init_object(B) cachefiles_ondemand_send_req(OPEN) // reuse msg_id 6 process_open_req copen 6,A.size // The expected failed copen was executed successfully Expect copen to fail, and when it does, it closes fd, which sets the object to close, and then close triggers reopen again. However, due to msg_id reuse resulting in a successful copen, the anonymous fd is not closed until the daemon exits. Therefore read requests waiting for reopen to complete may trigger hung task. To avoid this issue, allocate the msg_id cyclically to avoid reusing the msg_id for a very short duration of time.
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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