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amazonAmazonALAS2-2019-1165
HistoryMar 07, 2019 - 6:24 p.m.

Important: kernel

2019-03-0718:24:00
alas.aws.amazon.com
23

6.8 Medium

CVSS2

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

8.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

7.1 High

AI Score

Confidence

High

0.036 Low

EPSS

Percentile

91.7%

Issue Overview:

A use-after-free vulnerability was found in the way the Linux kernel’s KVM hypervisor implements its device control API. While creating a device via kvm_ioctl_create_device(), the device holds a reference to a VM object, later this reference is transferred to the caller’s file descriptor table. If such file descriptor was to be closed, reference count to the VM object could become zero, potentially leading to a use-after-free issue. A user/process could use this flaw to crash the guest VM resulting in a denial of service issue or, potentially, gain privileged access to a system.(CVE-2019-6974)

An information leakage issue was found in the way Linux kernel’s KVM hypervisor handled page fault exceptions while emulating instructions like VMXON, VMCLEAR, VMPTRLD, and VMWRITE with memory address as an operand. It occurs if the operand is a mmio address, as the returned exception object holds uninitialized stack memory contents. A guest user/process could use this flaw to leak host’s stack memory contents to a guest.(CVE-2019-7222)

A use-after-free vulnerability was found in the way the Linux kernel’s KVM hypervisor emulates a preemption timer for L2 guests when nested (=1) virtualization is enabled. This high resolution timer(hrtimer) runs when a L2 guest is active. After VM exit, the sync_vmcs12() timer object is stopped. The use-after-free occurs if the timer object is freed before calling sync_vmcs12() routine. A guest user/process could use this flaw to crash the host kernel resulting in a denial of service or, potentially, gain privileged access to a system.(CVE-2019-7221)

Affected Packages:

kernel

Note:

This advisory is applicable to Amazon Linux 2 (AL2) Core repository. Visit this FAQ section for the difference between AL2 Core and AL2 Extras advisories.

Issue Correction:
Run yum update kernel to update your system.

New Packages:

aarch64:  
    kernel-4.14.101-91.76.amzn2.aarch64  
    kernel-headers-4.14.101-91.76.amzn2.aarch64  
    kernel-debuginfo-common-aarch64-4.14.101-91.76.amzn2.aarch64  
    perf-4.14.101-91.76.amzn2.aarch64  
    perf-debuginfo-4.14.101-91.76.amzn2.aarch64  
    python-perf-4.14.101-91.76.amzn2.aarch64  
    python-perf-debuginfo-4.14.101-91.76.amzn2.aarch64  
    kernel-tools-4.14.101-91.76.amzn2.aarch64  
    kernel-tools-devel-4.14.101-91.76.amzn2.aarch64  
    kernel-tools-debuginfo-4.14.101-91.76.amzn2.aarch64  
    kernel-devel-4.14.101-91.76.amzn2.aarch64  
    kernel-debuginfo-4.14.101-91.76.amzn2.aarch64  
  
i686:  
    kernel-headers-4.14.101-91.76.amzn2.i686  
  
src:  
    kernel-4.14.101-91.76.amzn2.src  
  
x86_64:  
    kernel-4.14.101-91.76.amzn2.x86_64  
    kernel-headers-4.14.101-91.76.amzn2.x86_64  
    kernel-debuginfo-common-x86_64-4.14.101-91.76.amzn2.x86_64  
    perf-4.14.101-91.76.amzn2.x86_64  
    perf-debuginfo-4.14.101-91.76.amzn2.x86_64  
    python-perf-4.14.101-91.76.amzn2.x86_64  
    python-perf-debuginfo-4.14.101-91.76.amzn2.x86_64  
    kernel-tools-4.14.101-91.76.amzn2.x86_64  
    kernel-tools-devel-4.14.101-91.76.amzn2.x86_64  
    kernel-tools-debuginfo-4.14.101-91.76.amzn2.x86_64  
    kernel-devel-4.14.101-91.76.amzn2.x86_64  
    kernel-debuginfo-4.14.101-91.76.amzn2.x86_64  

Additional References

Red Hat: CVE-2019-6974, CVE-2019-7221, CVE-2019-7222

Mitre: CVE-2019-6974, CVE-2019-7221, CVE-2019-7222

6.8 Medium

CVSS2

Attack Vector

NETWORK

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

8.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

7.1 High

AI Score

Confidence

High

0.036 Low

EPSS

Percentile

91.7%