Bug 1595143 (CVE-2018-12904) - CVE-2018-12904 kernel: kvm: nVMX: missing privilege check allows privilege escalation in nested virtualization
Summary: CVE-2018-12904 kernel: kvm: nVMX: missing privilege check allows privilege es...
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2018-12904
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1595145 1595146
Blocks: 1595148
TreeView+ depends on / blocked
 
Reported: 2018-06-26 08:42 UTC by Adam Mariš
Modified: 2021-02-17 00:04 UTC (History)
43 users (show)

Fixed In Version: kernel 4.17.2
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Last Closed: 2019-07-12 13:05:42 UTC
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Description Adam Mariš 2018-06-26 08:42:45 UTC 
It was found that KVM virtualizing another hypervisor as L1 VM does not verify that VMX instructions from L1 VM (which trigger a VM exit and are emulated by L0 KVM) are coming from ring 0. This means that a normal user space program running in the L1 VM can trigger KVMs VMX emulation which gives a large number of privilege escalation vectors. This issue happens only if L2 guest is running, since VMX emulation code checks for the guests CR4.VMXE value.

This allows attacker in L2 guest to break out e.g. by exploiting a bug in L1 qemu process and using this bug for privilege escalation on the L1 system.

Bug report:

https://bugs.chromium.org/p/project-zero/issues/detail?id=1589

Upstream patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/x86/kvm?id=727ba748e110b4de50d142edca9d6a9b7e6111d8
Comment 1 Adam Mariš 2018-06-26 08:43:47 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1595146]
Comment 3 Adam Mariš 2018-06-27 12:30:59 UTC 
CVE known via:

http://seclists.org/oss-sec/2018/q2/246
Comment 4 Prasad Pandit 2018-08-29 18:54:47 UTC 
Statement:

This issue does not affect the versions of the kernel package as shipped with
Red Hat Enterprise Linux 5, 6, 7 and Red Hat Enterprise MRG 2.
Comment 7 Product Security DevOps Team 2019-07-12 13:05:42 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2018-12904
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