CVE-2015-8812
Description
A use-after-free flaw was found in the CXGB3 kernel driver when the network was considered to be congested. The kernel incorrectly misinterpreted the congestion as an error condition and incorrectly freed or cleaned up the socket buffer (skb). When the device then sent the skb's queued data, these structures were referenced. A local attacker could use this flaw to panic the system (denial of service) or, with a local account, escalate their privileges.
Statement
This issue affects the Linux kernels as shipped with Red Hat Enterprise Linux 5, 6 and 7 and Red Hat Enterprise MRG 2 and realtime kernels and may be addressed in a future update.
This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates in Red Hat Enterprise Linux 5 and 6 . 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).
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.9 | 10 | N/A |
| Attack Vector | Local | Network | N/A |
| Access Complexity | Medium | Low | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | Complete | Complete | N/A |
| Integrity Impact | Complete | Complete | N/A |
| Availability Impact | Complete | Complete | N/A |
Vector
Red Hat: AV:L/AC:M/Au:N/C:C/I:C/A:C
NVD: AV:N/AC:L/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.
Acknowledgements
This issue was discovered by Venkatesh Pottem (Red Hat Engineering).
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