Linux: Double Free
CVE-2022-48740 is a high-severity double 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 f446089a268c8fc6908488e991d28a9b936293db, 70caa32e6d81f45f0702070c0e4dfe945e92fbd7, 7ed9cbf7ac0d4ed86b356e1b944304ae9ee450d4 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 0.24% 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 f446089a268c8fc6908488e991d28a9b936293db or 70caa32e6d81f45f0702070c0e4dfe945e92fbd7 or 7ed9cbf7ac0d4ed86b356e1b944304ae9ee450d4 or 186edf7e368c40d06cf727a1ad14698ea67b74ad, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.99 or 5.15.22 or 5.16.8, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 60abd3181db29ea81742106cc0ac2e27fd05b418 up to, but not including, f446089a268c8fc6908488e991d28a9b936293db; 60abd3181db29ea81742106cc0ac2e27fd05b418 up to, but not including, 70caa32e6d81f45f0702070c0e4dfe945e92fbd7; 60abd3181db29ea81742106cc0ac2e27fd05b418 up to, but not including, 7ed9cbf7ac0d4ed86b356e1b944304ae9ee450d4; 60abd3181db29ea81742106cc0ac2e27fd05b418 up to, but not including, 186edf7e368c40d06cf727a1ad14698ea67b74ad; 5.7 | f446089a268c8fc6908488e991d28a9b936293db, 70caa32e6d81f45f0702070c0e4dfe945e92fbd7, 7ed9cbf7ac0d4ed86b356e1b944304ae9ee450d4, 186edf7e368c40d06cf727a1ad14698ea67b74ad |
| Linux | Linux Kernel | 5.7 up to, but not including, 5.10.99; 5.11 up to, but not including, 5.15.22; 5.16 up to, but not including, 5.16.8; 5.17 | 5.10.99, 5.15.22, 5.16.8 |
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: selinux: fix double free of cond_list on error paths On error path from cond_read_list() and duplicate_policydb_cond_list() the cond_list_destroy() gets called a second time in caller functions, resulting in NULL pointer deref. Fix this by resetting the cond_list_len to 0 in cond_list_destroy(), making subsequent calls a noop. Also consistently reset the cond_list pointer to NULL after freeing. [PM: fix line lengths in the description]
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
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
Recent Double Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.1 High severity
- 8.8 High severity
- 7.8 High severity
- 7.8 High severity
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