Linux: Use After Free
CVE-2022-49291 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 a42aa926843acca96c0dfbde2e835b8137f2f092, 9cb6c40a6ebe4a0cfc9d6a181958211682cffea9, fbeb492694ce0441053de57699e1e2b7bc148a69 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 0.3% 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 a42aa926843acca96c0dfbde2e835b8137f2f092 or 9cb6c40a6ebe4a0cfc9d6a181958211682cffea9 or fbeb492694ce0441053de57699e1e2b7bc148a69 or 0f6947f5f5208f6ebd4d76a82a4757e2839a23f8, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.14.279 or 4.19.243 or 5.4.193 or 5.10.109, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, a42aa926843acca96c0dfbde2e835b8137f2f092; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 9cb6c40a6ebe4a0cfc9d6a181958211682cffea9; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, fbeb492694ce0441053de57699e1e2b7bc148a69; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 0f6947f5f5208f6ebd4d76a82a4757e2839a23f8; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 33061d0fba51d2bf70a2ef9645f703c33fe8e438; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 0090c13cbbdffd7da079ac56f80373a9a1be0bf8; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 1bbf82d9f961414d6c76a08f7f843ea068e0ab7b; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 92ee3c60ec9fe64404dc035e7c41277d74aa26cb; and 1 more ranges | a42aa926843acca96c0dfbde2e835b8137f2f092, 9cb6c40a6ebe4a0cfc9d6a181958211682cffea9, fbeb492694ce0441053de57699e1e2b7bc148a69, 0f6947f5f5208f6ebd4d76a82a4757e2839a23f8, 33061d0fba51d2bf70a2ef9645f703c33fe8e438, 0090c13cbbdffd7da079ac56f80373a9a1be0bf8 |
| Linux | Linux Kernel | before 4.14.279; 4.15 up to, but not including, 4.19.243; 4.20 up to, but not including, 5.4.193; 5.5 up to, but not including, 5.10.109; 5.11 up to, but not including, 5.15.32; 5.16 up to, but not including, 5.16.18; 5.17 up to, but not including, 5.17.1 | 4.14.279, 4.19.243, 5.4.193, 5.10.109, 5.15.32, 5.16.18 |
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: ALSA: pcm: Fix races among concurrent hw_params and hw_free calls Currently we have neither proper check nor protection against the concurrent calls of PCM hw_params and hw_free ioctls, which may result in a UAF. Since the existing PCM stream lock can't be used for protecting the whole ioctl operations, we need a new mutex to protect those racy calls. This patch introduced a new mutex, runtime->buffer_mutex, and applies it to both hw_params and hw_free ioctl code paths. Along with it, the both functions are slightly modified (the mmap_count check is moved into the state-check block) for code simplicity.
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/0090c13cbbdffd7da079ac56f80373a9a1be0bf8
- git.kernel.org/stable/c/0f6947f5f5208f6ebd4d76a82a4757e2839a23f8
- git.kernel.org/stable/c/1bbf82d9f961414d6c76a08f7f843ea068e0ab7b
- git.kernel.org/stable/c/33061d0fba51d2bf70a2ef9645f703c33fe8e438
- git.kernel.org/stable/c/92ee3c60ec9fe64404dc035e7c41277d74aa26cb
- git.kernel.org/stable/c/9cb6c40a6ebe4a0cfc9d6a181958211682cffea9
- git.kernel.org/stable/c/a42aa926843acca96c0dfbde2e835b8137f2f092
- git.kernel.org/stable/c/fbeb492694ce0441053de57699e1e2b7bc148a69
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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