CVE-2023-0045

Name	CVE-2023-0045
Description	The current implementation of the prctl syscall does not issue an IBPB immediately during the syscall. The ib_prctl_set function updates the Thread Information Flags (TIFs) for the task and updates the SPEC_CTRL MSR on the function __speculation_ctrl_update, but the IBPB is only issued on the next schedule, when the TIF bits are checked. This leaves the victim vulnerable to values already injected on the BTB, prior to the prctl syscall. The patch that added the support for the conditional mitigation via prctl (ib_prctl_set) dates back to the kernel 4.9.176. We recommend upgrading past commit a664ec9158eeddd75121d39c9a0758016097fa96
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-3403-1, DLA-3404-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
linux (PTS)	bullseye	5.10.223-1	fixed
	bullseye (security)	5.10.234-1	fixed
	bookworm	6.1.129-1	fixed
	bookworm (security)	6.1.135-1	fixed
	sid, trixie	6.12.27-1	fixed

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

Package	Type	Release	Fixed Version	Origin
linux	source	buster	4.19.282-1	DLA-3403-1
linux	source	bullseye	5.10.178-1
linux	source	(unstable)	6.1.7-1
linux-5.10	source	buster	5.10.178-3~deb10u1	DLA-3404-1

Notes

https://www.openwall.com/lists/oss-security/2023/02/03/1
https://github.com/google/security-research/security/advisories/GHSA-9x5g-vmxf-4qj8#event-88245
https://git.kernel.org/linus/a664ec9158eeddd75121d39c9a0758016097fa96 (6.2-rc3)
https://github.com/es0j/CVE-2023-0045