Linux: Use After Free
CVE-2022-49168 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 e7e1d15d2bd8c373cf621614ddd17971a2132713, 7170875083254b51fcc5d67f96640977083f481e, e76c78c48902dae6fa612749f59162bca0a79e0b 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 0.33% 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 e7e1d15d2bd8c373cf621614ddd17971a2132713 or 7170875083254b51fcc5d67f96640977083f481e or e76c78c48902dae6fa612749f59162bca0a79e0b or d1cb11fb45ebbb1e7dfe5e9038b32ea72c184b14, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.248 or 5.15.184 or 5.16.19 or 5.17.2, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 6c387ab20db15f2bd448f7c508e2638101b16ea1 up to, but not including, e7e1d15d2bd8c373cf621614ddd17971a2132713; 6c387ab20db15f2bd448f7c508e2638101b16ea1 up to, but not including, 7170875083254b51fcc5d67f96640977083f481e; 6c387ab20db15f2bd448f7c508e2638101b16ea1 up to, but not including, e76c78c48902dae6fa612749f59162bca0a79e0b; 6c387ab20db15f2bd448f7c508e2638101b16ea1 up to, but not including, d1cb11fb45ebbb1e7dfe5e9038b32ea72c184b14; 6c387ab20db15f2bd448f7c508e2638101b16ea1 up to, but not including, 8cbc3001a3264d998d6b6db3e23f935c158abd4d; 3.18 | e7e1d15d2bd8c373cf621614ddd17971a2132713, 7170875083254b51fcc5d67f96640977083f481e, e76c78c48902dae6fa612749f59162bca0a79e0b, d1cb11fb45ebbb1e7dfe5e9038b32ea72c184b14, 8cbc3001a3264d998d6b6db3e23f935c158abd4d |
| Linux | Linux Kernel | before 5.10.248; 5.11 up to, but not including, 5.15.184; 5.16 up to, but not including, 5.16.19; 5.17 up to, but not including, 5.17.2 | 5.10.248, 5.15.184, 5.16.19, 5.17.2 |
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 CISA (ADP).
Official description
In the Linux kernel, the following vulnerability has been resolved: btrfs: do not clean up repair bio if submit fails The submit helper will always run bio_endio() on the bio if it fails to submit, so cleaning up the bio just leads to a variety of use-after-free and NULL pointer dereference bugs because we race with the endio function that is cleaning up the bio. Instead just return BLK_STS_OK as the repair function has to continue to process the rest of the pages, and the endio for the repair bio will do the appropriate cleanup for the page that it was given.
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: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/7170875083254b51fcc5d67f96640977083f481e
- git.kernel.org/stable/c/8cbc3001a3264d998d6b6db3e23f935c158abd4d
- git.kernel.org/stable/c/d1cb11fb45ebbb1e7dfe5e9038b32ea72c184b14
- git.kernel.org/stable/c/e76c78c48902dae6fa612749f59162bca0a79e0b
- git.kernel.org/stable/c/e7e1d15d2bd8c373cf621614ddd17971a2132713
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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