Linux: Use After Free
CVE-2022-50454 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 56ee9577915dc06f55309901012a9ef68dbdb5a8, 5d6093c49c098d86c7b136aba9922df44aeb6944, 861f085f81fd569b02cc2c11165a9e6cca144424 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 0.16% 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 56ee9577915dc06f55309901012a9ef68dbdb5a8 or 5d6093c49c098d86c7b136aba9922df44aeb6944 or 861f085f81fd569b02cc2c11165a9e6cca144424 or 3aeda2fe6517cc52663d4ce3588dd43f0d4124a7, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.4.220 or 5.10.150 or 5.15.75 or 5.19.17, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 019cbd4a4feb3aa3a917d78e7110e3011bbff6d5 up to, but not including, 56ee9577915dc06f55309901012a9ef68dbdb5a8; 019cbd4a4feb3aa3a917d78e7110e3011bbff6d5 up to, but not including, 5d6093c49c098d86c7b136aba9922df44aeb6944; 019cbd4a4feb3aa3a917d78e7110e3011bbff6d5 up to, but not including, 861f085f81fd569b02cc2c11165a9e6cca144424; 019cbd4a4feb3aa3a917d78e7110e3011bbff6d5 up to, but not including, 3aeda2fe6517cc52663d4ce3588dd43f0d4124a7; 019cbd4a4feb3aa3a917d78e7110e3011bbff6d5 up to, but not including, 7d80473e9f12548ac05b36af4fb9ce80f2f73509; 019cbd4a4feb3aa3a917d78e7110e3011bbff6d5 up to, but not including, 540dfd188ea2940582841c1c220bd035a7db0e51; 5.4 | 56ee9577915dc06f55309901012a9ef68dbdb5a8, 5d6093c49c098d86c7b136aba9922df44aeb6944, 861f085f81fd569b02cc2c11165a9e6cca144424, 3aeda2fe6517cc52663d4ce3588dd43f0d4124a7, 7d80473e9f12548ac05b36af4fb9ce80f2f73509, 540dfd188ea2940582841c1c220bd035a7db0e51 |
| Linux | Linux Kernel | 5.4 up to, but not including, 5.4.220; 5.5 up to, but not including, 5.10.150; 5.11 up to, but not including, 5.15.75; 5.16 up to, but not including, 5.19.17; 6.0 up to, but not including, 6.0.3 | 5.4.220, 5.10.150, 5.15.75, 5.19.17, 6.0.3 |
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 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
In the Linux kernel, the following vulnerability has been resolved: drm/nouveau: fix a use-after-free in nouveau_gem_prime_import_sg_table() nouveau_bo_init() is backed by ttm_bo_init() and ferries its return code back to the caller. On failures, ttm will call nouveau_bo_del_ttm() and free the memory.Thus, when nouveau_bo_init() returns an error, the gem object has already been released. Then the call to nouveau_bo_ref() will use the freed "nvbo->bo" and lead to a use-after-free bug. We should delete the call to nouveau_bo_ref() to avoid the use-after-free.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/3aeda2fe6517cc52663d4ce3588dd43f0d4124a7
- git.kernel.org/stable/c/540dfd188ea2940582841c1c220bd035a7db0e51
- git.kernel.org/stable/c/56ee9577915dc06f55309901012a9ef68dbdb5a8
- git.kernel.org/stable/c/5d6093c49c098d86c7b136aba9922df44aeb6944
- git.kernel.org/stable/c/7d80473e9f12548ac05b36af4fb9ce80f2f73509
- git.kernel.org/stable/c/861f085f81fd569b02cc2c11165a9e6cca144424
Recent Use After Free vulnerabilities
- 8.1 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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