CVE-2018-18021

Published: 7 October 2018

arch/arm64/kvm/guest.c in KVM in the Linux kernel before 4.18.12 on the arm64 platform mishandles the KVM_SET_ON_REG ioctl. This is exploitable by attackers who can create virtual machines. An attacker can arbitrarily redirect the hypervisor flow of control (with full register control). An attacker can also cause a denial of service (hypervisor panic) via an illegal exception return. This occurs because of insufficient restrictions on userspace access to the core register file, and because PSTATE.M validation does not prevent unintended execution modes.

From the Ubuntu Security Team

It was discovered that the KVM implementation in the Linux kernel on ARM 64bit processors did not properly handle some ioctls. An attacker with the privilege to create KVM-based virtual machines could use this to cause a denial of service (host system crash) or execute arbitrary code in the host.

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18021
• https://git.kernel.org/linus/d26c25a9d19b5976b319af528886f89cf455692d
• https://git.kernel.org/linus/2a3f93459d689d990b3ecfbe782fec89b97d3279
• http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2a3f93459d689d990b3ecfbe782fec89b97d3279
• http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d26c25a9d19b5976b319af528886f89cf455692d
• https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.12
• https://github.com/torvalds/linux/commit/2a3f93459d689d990b3ecfbe782fec89b97d3279
• https://github.com/torvalds/linux/commit/d26c25a9d19b5976b319af528886f89cf455692d
• https://www.openwall.com/lists/oss-security/2018/10/02/2
• https://ubuntu.com/security/notices/USN-3821-1
• https://ubuntu.com/security/notices/USN-3821-2
• https://ubuntu.com/security/notices/USN-3931-1
• https://ubuntu.com/security/notices/USN-3931-2
• NVD
• Launchpad
• Debian