CVE-2015-5166
Description
A flaw has been found in the QEMU emulator built with IDE Emulation PCI PIIX3/4 support; the emulator is vulnerable to a use-after-free flaw, while writing data to an I/O port inside a guest. This issue is specific to the Xen platform. A privileged(CAP_SYS_RAWIO) guest user on the Xen platform could use this flaw to crash the QEMU instance or attempt to make a guest escape to QEMU-process privileges.
Statement
This issue does not affect the versions of kvm and xen packages as shipped with Red Hat Enterprise Linux 5.
This issue does not affect the versions of the qemu-kvm packages as shipped with Red Hat Enterprise Linux 6.
This issue does not affect the Red Hat Enterprise Linux 6 based versions of qemu-kvm-rhev packages as shipped with Red Hat Enterprise Virtualization 3.
This issue does not affect the versions of the qemu-kvm packages as shipped with Red Hat Enterprise Linux 7.
This issue does not affect the Red Hat Enterprise Linux 7 based versions of the qemu-kvm-rhev packages as shipped with Red Hat Enterprise Virtualization 3.
This issue does not affect the qemu-kvm-rhev packages as shipped with any currently supported versions of Red Hat Enterprise Linux OpenStack Platform.
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 v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 2.9 | 7.2 | N/A |
| Attack Vector | Adjacent Network | Local | N/A |
| Access Complexity | Medium | Low | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | None | Complete | N/A |
| Integrity Impact | None | Complete | N/A |
| Availability Impact | Partial | Complete | N/A |
Vector
Red Hat: AV:A/AC:M/Au:N/C:N/I:N/A:P
NVD: AV:L/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
Red Hat would like to thank Xen project for reporting this issue. Upstream acknowledges Donghai Zhu (Alibaba) as the original reporter.
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