CVE-2023-1998

NameCVE-2023-1998
DescriptionThe Linux kernel allows userspace processes to enable mitigations by calling prctl with PR_SET_SPECULATION_CTRL which disables the speculation feature as well as by using seccomp. We had noticed that on VMs of at least one major cloud provider, the kernel still left the victim process exposed to attacks in some cases even after enabling the spectre-BTI mitigation with prctl. The same behavior can be observed on a bare-metal machine when forcing the mitigation to IBRS on boot command line. This happened because when plain IBRS was enabled (not enhanced IBRS), the kernel had some logic that determined that STIBP was not needed. The IBRS bit implicitly protects against cross-thread branch target injection. However, with legacy IBRS, the IBRS bit was cleared on returning to userspace, due to performance reasons, which disabled the implicit STIBP and left userspace threads vulnerable to cross-thread branch target injection against which STIBP protects.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-3403-1, DLA-3404-1, ELA-845-1, ELA-847-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)jessie, jessie (lts)3.16.84-1vulnerable
stretch (security)4.9.320-2vulnerable
stretch (lts), stretch4.9.320-3vulnerable
buster4.19.249-2vulnerable
buster (security)4.19.316-1fixed
bullseye5.10.218-1fixed
bullseye (security)5.10.221-1fixed
bookworm6.1.94-1fixed
bookworm (security)6.1.99-1fixed
trixie6.9.8-1fixed
sid6.9.9-1fixed
linux-4.19 (PTS)jessie, jessie (lts)4.19.316-1~deb8u1fixed
stretch (security)4.19.232-1~deb9u1vulnerable
stretch (lts), stretch4.19.316-1~deb9u1fixed
linux-5.10 (PTS)stretch (lts), stretch5.10.218-1~deb9u1fixed
buster (security)5.10.218-1~deb10u1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcejessie(unfixed)end-of-life
linuxsourcestretch(unfixed)end-of-life
linuxsourcebuster4.19.282-1DLA-3403-1
linuxsourcebullseye5.10.178-1
linuxsource(unstable)6.1.20-1
linux-4.19sourcejessie4.19.282-1~deb8u1ELA-847-1
linux-4.19sourcestretch4.19.282-1~deb9u1ELA-847-1
linux-5.10sourcestretch5.10.178-3~deb9u1ELA-845-1
linux-5.10sourcebuster5.10.178-3~deb10u1DLA-3404-1

Notes

https://git.kernel.org/linus/6921ed9049bc7457f66c1596c5b78aec0dae4a9d (6.3-rc1)
https://kernel.dance/#6921ed9049bc7457f66c1596c5b78aec0dae4a9d

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