SB20200114120 - Input validation error in xen (Alpine package)

Description

This security bulletin contains information about 1 security vulnerability.

1) Input validation error (CVE-ID: CVE-2019-19577)

The vulnerability allows a remote user to perform a denial of service (DoS) attack.

An issue was discovered in Xen through 4.12.x allowing x86 AMD HVM guest OS users to cause a denial of service or possibly gain privileges by triggering data-structure access during pagetable-height updates. When running on AMD systems with an IOMMU, Xen attempted to dynamically adapt the number of levels of pagetables (the pagetable height) in the IOMMU according to the guest's address space size. The code to select and update the height had several bugs. Notably, the update was done without taking a lock which is necessary for safe operation. A malicious guest administrator can cause Xen to access data structures while they are being modified, causing Xen to crash.

Remediation

Install update from vendor's website.

References

• https://git.alpinelinux.org/aports/commit/?id=95332e4ed106c72d58a0a5490d0f608e3d76b83e
• https://git.alpinelinux.org/aports/commit/?id=05b5ec57508952a3bf13538e1f72d2a5e9357796
• https://git.alpinelinux.org/aports/commit/?id=29678cb92eeeb6dc96ec2e86481345797474ddb8
• https://git.alpinelinux.org/aports/commit/?id=6a020fa149b82307ca356d1a3fe861420eb56d49
• https://git.alpinelinux.org/aports/commit/?id=58d7b94f0134f00815145d95ee720d36d645c72e
• https://git.alpinelinux.org/aports/commit/?id=5b04af6c9b65512ad9ff6f687e8651189bd186c5
• https://git.alpinelinux.org/aports/commit/?id=8d6c01f17f4285e0142442bb8afcce72f4bd280b