CVE-2023-46841

NameCVE-2023-46841
DescriptionRecent x86 CPUs offer functionality named Control-flow Enforcement Technology (CET). A sub-feature of this are Shadow Stacks (CET-SS). CET-SS is a hardware feature designed to protect against Return Oriented Programming attacks. When enabled, traditional stacks holding both data and return addresses are accompanied by so called "shadow stacks", holding little more than return addresses. Shadow stacks aren't writable by normal instructions, and upon function returns their contents are used to check for possible manipulation of a return address coming from the traditional stack. In particular certain memory accesses need intercepting by Xen. In various cases the necessary emulation involves kind of replaying of the instruction. Such replaying typically involves filling and then invoking of a stub. Such a replayed instruction may raise an exceptions, which is expected and dealt with accordingly. Unfortunately the interaction of both of the above wasn't right: Recovery involves removal of a call frame from the (traditional) stack. The counterpart of this operation for the shadow stack was missing.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
xen (PTS)buster, buster (security)4.11.4+107-gef32c7afa2-1fixed
bullseye4.14.6-1vulnerable
bullseye (security)4.14.5+94-ge49571868d-1vulnerable
bookworm4.17.3+10-g091466ba55-1~deb12u1vulnerable
trixie4.17.3+10-g091466ba55-1vulnerable
sid4.17.3+36-g54dacb5c02-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
xensourcebuster(not affected)
xensourcebullseye(unfixed)end-of-life
xensource(unstable)4.17.3+36-g54dacb5c02-1

Notes

[bookworm] - xen <postponed> (Minor issue, fix along in next DSA)
[bullseye] - xen <end-of-life> (EOLed in Bullseye)
[buster] - xen <not-affected> (Vulnerable code not present)
https://xenbits.xen.org/xsa/advisory-451.html

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