CVE-2017-15265
Description
A use-after-free vulnerability was found when issuing an ioctl to a sound device. This could allow a user to exploit a race condition and create memory corruption or possibly privilege escalation.
Statement
This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 5,6, 7, realtime and MRG-2.
Red Hat Enterprise Linux 5 has transitioned to Production phase 3.
During the Production 3 Phase, Critical impact Security Advisories (RHSAs)
and selected Urgent Priority Bug Fix Advisories (RHBAs) may be released
as they become available.
The official life cycle policy can be reviewed here:
http://redhat.com/rhel/lifecycle
Future Linux kernel updates for the respective releases may address this issue.
Mitigation
It is possible to prevent the affected code from being loaded by blacklisting the kernel module snd_seq. Instructions relating to how to blacklist a kernel module are shown here: https://access.redhat.com/solutions/41278
Alternatively a custom permission set can be created by udev, the correct permissions will depend on your use case. Please contact Red Hat customer support for creating a rule set that can minimize flaw exposure.
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 | 5.5 | 7 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | High | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | High | N/A |
| Integrity Impact | None | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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