CVE-2023-0045

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 4.9.176

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.

Recommendations Upgrade past commit a664ec9158eeddd75121d39c9a0758016097fa96 to mitigate the issue. As a temporary workaround, consider disabling the ib prctl set function until a patch is available. Restrict access to the vulnerable module to minimize the risk of exploitation. Avoid using the ib prctl set function in the affected API endpoint until the issue is resolved.