Linux: Use After Free
CVE-2022-49223 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 518bb96367123062b48b0a9842f2864249b565f6, b0022ca445d5fc4d0c89d15dcd0f855977b22c1d, 49f2dab77a5e1354f5da6ccdc9346a8212697be2 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 0.27% 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 518bb96367123062b48b0a9842f2864249b565f6 or b0022ca445d5fc4d0c89d15dcd0f855977b22c1d or 49f2dab77a5e1354f5da6ccdc9346a8212697be2 or 74be98774dfbc5b8b795db726bd772e735d2edd4, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.54 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 | 40ba17afdfabb01688c61565dbe02a916241bc05 up to, but not including, 518bb96367123062b48b0a9842f2864249b565f6; 40ba17afdfabb01688c61565dbe02a916241bc05 up to, but not including, b0022ca445d5fc4d0c89d15dcd0f855977b22c1d; 40ba17afdfabb01688c61565dbe02a916241bc05 up to, but not including, 49f2dab77a5e1354f5da6ccdc9346a8212697be2; 40ba17afdfabb01688c61565dbe02a916241bc05 up to, but not including, 74be98774dfbc5b8b795db726bd772e735d2edd4; 5.14 | 518bb96367123062b48b0a9842f2864249b565f6, b0022ca445d5fc4d0c89d15dcd0f855977b22c1d, 49f2dab77a5e1354f5da6ccdc9346a8212697be2, 74be98774dfbc5b8b795db726bd772e735d2edd4 |
| Linux | Linux Kernel | 5.14 up to, but not including, 5.15.54; 5.16 up to, but not including, 5.16.19; 5.17 up to, but not including, 5.17.2 | 5.15.54, 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: cxl/port: Hold port reference until decoder release KASAN + DEBUG_KOBJECT_RELEASE reports a potential use-after-free in cxl_decoder_release() where it goes to reference its parent, a cxl_port, to free its id back to port->decoder_ida. BUG: KASAN: use-after-free in to_cxl_port+0x18/0x90 [cxl_core] Read of size 8 at addr ffff888119270908 by task kworker/35:2/379 CPU: 35 PID: 379 Comm: kworker/35:2 Tainted: G OE 5.17.0-rc2+ #198 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Workqueue: events kobject_delayed_cleanup Call Trace: <TASK> dump_stack_lvl+0x59/0x73 print_address_description.constprop.0+0x1f/0x150 ? to_cxl_port+0x18/0x90 [cxl_core] kasan_report.cold+0x83/0xdf ? to_cxl_port+0x18/0x90 [cxl_core] to_cxl_port+0x18/0x90 [cxl_core] cxl_decoder_release+0x2a/0x60 [cxl_core] device_release+0x5f/0x100 kobject_cleanup+0x80/0x1c0 The device core only guarantees parent lifetime until all children are unregistered. If a child needs a parent to complete its ->release() callback that child needs to hold a reference to extend the lifetime of the parent.
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
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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