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Bug 643342 (CVE-2017-5715)

Summary: [TRACKER] hw: cpu: speculative execution branch target injection (CVE-2017-5715)
Product: Gentoo Security Reporter: GLSAMaker/CVETool Bot <glsamaker>
Component: VulnerabilitiesAssignee: Gentoo Security <security>
Status: IN_PROGRESS ---    
Severity: normal CC: capsel+bugzillagentoo, gentoo-bugzilla, guillaume, kfm, mentalstring, pacho, peter.volkov, randy, remy, sam, sergeev917
Priority: Normal Keywords: Tracker
Version: unspecified   
Hardware: All   
OS: Linux   
See Also: https://bugs.gentoo.org/show_bug.cgi?id=646076
Whiteboard:
Package list:
Runtime testing required: ---
Bug Depends on: 646758, 643350, 643352, 643430, 643432, 643476, 643764, 643794, 643808, 644128, 645510    
Bug Blocks: 643228    

Description GLSAMaker/CVETool Bot gentoo-dev 2018-01-04 01:02:22 UTC
Incoming details.
Comment 1 Thomas Deutschmann gentoo-dev Security 2018-01-04 01:11:04 UTC
An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of instructions (a commonly used performance optimization). There are three primary variants of the issue which differ in the way the speculative execution can be exploited.

Variant CVE-2017-5715 triggers the speculative execution by utilizing branch target injection. It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory accesses may cause allocation into the microprocessor's data cache even for speculatively executed instructions that never actually commit (retire). As a result, an unprivileged attacker could use this flaw to cross the syscall and guest/host boundaries and read privileged memory by conducting targeted cache side-channel attacks.

Source: https://bugzilla.redhat.com/show_bug.cgi?id=1519780


External References:

https://access.redhat.com/security/vulnerabilities/speculativeexecution
https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html
https://spectreattack.com/
https://meltdownattack.com
Comment 2 Thomas Deutschmann gentoo-dev Security 2018-01-04 01:22:00 UTC
Converting into tracker bug, needed for Xen as well.
Comment 3 Kerin Millar 2018-02-07 04:11:00 UTC
Just linking a post by David Woodhouse here, as is greatly clarifies the various mitigation techiques that have been devised. An important aspect of the present situation is that retpolines, alone, constitute a viable mitigation technique for CVE-2017-5715 - but not wholly so if using Skylake or newer.

https://lkml.org/lkml/2018/1/22/598