CVE-2016-7911
Description
A use-after-free vulnerability in sys_ioprio_get() was found due to get_task_ioprio() accessing the task->io_context without holding the task lock and could potentially race with exit_io_context(), leading to a use-after-free.
Statement
This issue affects the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 6, 7 and Red Hat Enterprise MRG 2. Future kernel updates for Red Hat Enterprise Linux 6, 7 and Red Hat Enterprise MRG 2 are not planning to be updated to address this issue. If this affects you please lodge a support request.
Red Hat Enterprise Linux 5 is now in Production 3 phase of the support and maintenance life cycle. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.7 | 7.8 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | Low | None | N/A |
| User Interaction | None | Required | 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:H/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4 | 9.3 | N/A |
| Attack Vector | Local | Network | N/A |
| Access Complexity | High | Medium | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | None | Complete | N/A |
| Integrity Impact | None | Complete | 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:N/AC:M/Au:N/C:C/I:C/A:C
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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