It was found that the Linux kernel's ping socket implementation did not properly handle socket unhashing during spurious disconnects, which could lead to a use-after-free flaw. On x86-64 architecture systems, a local user able to create ping sockets could use this flaw to crash the system. On non-x86-64 architecture systems, a local user able to create ping sockets could use this flaw to escalate their privileges on the system.
Find out more about CVE-2015-3636 from the MITRE CVE dictionary dictionary and NIST NVD.
This issue does not affect the Linux kernel as shipped with Red Hat Enterprise Linux 5. This issue does affect the Linux kernel as shipped with Red Hat Enterprise Linux 6, 7 and Red Hat Enterprise MRG 2. Future kernel updates for the respective releases will address this issue.
Please note that on x86-64 architecture systems the impact is limited to local Denial of Service and that the ping sockets functionality is disabled by default (net.ipv4.ping_group_range sysctl is "1 0").
| Base Score | 6 |
|---|---|
| Base Metrics | AV:L/AC:H/Au:S/C:C/I:C/A:C |
| Access Vector | Local |
| Access Complexity | High |
| Authentication | Single |
| Confidentiality Impact | Complete |
| Integrity Impact | Complete |
| Availability Impact | Complete |
Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).
| Platform | Errata | Release Date |
|---|---|---|
| Red Hat Enterprise Linux for Real Time for NFV (v. 7) (kernel-rt) | RHSA-2015:1565 | 2015-08-05 |
| Red Hat Enterprise Linux 7 (kernel) | RHSA-2015:1534 | 2015-08-06 |
| Red Hat Enterprise Linux 6 (kernel) | RHSA-2015:1221 | 2015-07-14 |
| Red Hat Enterprise Linux Extended Update Support 6.5 (kernel) | RHSA-2015:1583 | 2015-08-11 |
| Red Hat MRG Grid for RHEL 6 Server v.2 (kernel-rt) | RHSA-2015:1564 | 2015-08-05 |
| Red Hat Enterprise Linux Advanced Update Support 6.4 (kernel) | RHSA-2015:1643 | 2015-08-18 |
| Platform | Package | State |
|---|---|---|
| Red Hat Enterprise Linux 5 | kernel | Not affected |
You can check whether ping socket functionality is enabled by examining the net.ipv4.ping_group_range sysctl value:
~]# sysctl net.ipv4.ping_group_range
net.ipv4.ping_group_range = 1 0
"1 0" is the default value and disables the ping socket functionality even for root user. Any other value means that the ping socket functionality might be enabled for certain users on the system.
To mitigate this vulnerability make sure that you either allow the functionality to trusted local users (groups) only or set the net.ipv4.ping_group_range sysctl to the default and disabled state:
~]# sysctl net.ipv4.ping_group_range="1 0"
Please note that this might prevent some programs relying on this functionality from functioning properly.
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