CVE-2016-6213

fs/namespace.c in the Linux kernel before 4.9 does not restrict how many mounts may exist in a mount namespace, which allows local users to cause a denial of service (memory consumption and deadlock) via MS_BIND mount system calls, as demonstrated by a loop that triggers exponential growth in the number of mounts.

Weakness

The product does not properly control the allocation and maintenance of a limited resource.

Affected Software

Potential Mitigations

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d29216842a85c7970c536108e093963f02714498
• http://www.openwall.com/lists/oss-security/2016/07/13/8
• http://www.securityfocus.com/bid/91754
• https://access.redhat.com/errata/RHSA-2017:1842
• https://access.redhat.com/errata/RHSA-2017:2077
• https://bugzilla.redhat.com/show_bug.cgi?id=1356471
• https://github.com/torvalds/linux/commit/d29216842a85c7970c536108e093963f02714498
• http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d29216842a85c7970c536108e093963f02714498
• http://www.openwall.com/lists/oss-security/2016/07/13/8
• http://www.securityfocus.com/bid/91754
• https://access.redhat.com/errata/RHSA-2017:1842
• https://access.redhat.com/errata/RHSA-2017:2077
• https://bugzilla.redhat.com/show_bug.cgi?id=1356471
• https://github.com/torvalds/linux/commit/d29216842a85c7970c536108e093963f02714498