CVE-2015-4692
Description
A DoS flaw was found for a Linux kernel built for the x86 architecture which had the KVM virtualization support(CONFIG_KVM) enabled. The kernel would be vulnerable to a NULL pointer dereference flaw in Linux kernel's kvm_apic_has_events() function while doing an ioctl. An unprivileged user able to access the "/dev/kvm" device could use this flaw to crash the system kernel.
Statement
This issue does not affect the versions of Linux kernel as shipped with Red Hat Enterprise Linux 5, 6 and Red Hat Enterprise MRG 2.
This issue affects the version of the kernel package as shipped with Red Hat Enterprise Linux 7.
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 | 4.7 | 4.9 | N/A |
| Attack Vector | Local | Local | N/A |
| Access Complexity | Medium | Low | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | Complete | Complete | N/A |
Vector
Red Hat: AV:L/AC:M/Au:N/C:N/I:N/A:C
NVD: AV:L/AC:L/Au:N/C:N/I:N/A:C
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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