CVE-2021-44733
Description
A use-after-free flaw in the Linux kernel TEE (Trusted Execution Environment) subsystem was found in the way user calls ioctl TEE_IOC_OPEN_SESSION or TEE_IOC_INVOKE. A local user could use this flaw to crash the system or escalate their privileges on the system. If the Linux system non configured with the CONFIG_PREEMPT option or CONFIG_CPU_SW_DOMAIN_PAN option enabled, then it is unlikely that a user can trigger this issue.
Mitigation
To mitigate this issue, prevent the modules tee, trusted_tee from being loaded. Please see https://access.redhat.com/solutions/41278 for information on how to blacklist a kernel module to prevent it from loading automatically.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.4 | 7 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | None | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory; Read Application Data
When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The uninitialized resource may contain values that cause program flow to change in ways that the programmer did not intend.
Acknowledgements
Red Hat would like to thank Patrik Lantz (axis.com) for reporting this issue.
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