CVE-2017-12168

The access_pmu_evcntr function in arch/arm64/kvm/sys_regs.c in the Linux kernel before 4.8.11 allows privileged KVM guest OS users to cause a denial of service (assertion failure and host OS crash) by accessing the Performance Monitors Cycle Count Register (PMCCNTR).

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9e3f7a29694049edd728e2400ab57ad7553e5aa9
• http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.8.11
• https://bugzilla.redhat.com/show_bug.cgi?id=1492984
• https://github.com/torvalds/linux/commit/9e3f7a29694049edd728e2400ab57ad7553e5aa9
• http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9e3f7a29694049edd728e2400ab57ad7553e5aa9
• http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.8.11
• https://bugzilla.redhat.com/show_bug.cgi?id=1492984
• https://github.com/torvalds/linux/commit/9e3f7a29694049edd728e2400ab57ad7553e5aa9