CVE-2016-6213
Description
It was found that in Linux kernel the mount table expands by a power-of-two with each bind mount command. If a system is configured to allow non-privileged user to do bind mounts, or allows to do so in a container or unprivileged mount namespace, then non-privileged user is able to cause a local DoS by overflowing the mount table, which causes a deadlock for the whole system.
Statement
This issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 6, 7 and MRG-2 as of now due to the absence of unprivileged mount name spaces support.
Nevertheless, the unprivileged mount name spaces might be added to a future RHEL-7 version as a supported feature, so future Linux kernel updates for the respective releases might address this issue.
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 | 4.7 | 4.7 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4 | 4.7 | N/A |
| Attack Vector | Local | Local | N/A |
| Access Complexity | High | Medium | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | Complete | Complete | N/A |
Vector
Red Hat: AV:L/AC:H/Au:N/C:N/I:N/A:C
NVD: AV:L/AC:M/Au:N/C:N/I:N/A:C
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Acknowledgements
This issue was discovered by Qian Cai (Red Hat).
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