# CVE-2023-0045: linux: The current implementation of the prctl syscall does not issue an IBPB immediately during the syscall

CVE-2023-0045 is fixed in linux on 1 platform, first by DEBIAN-CVE-2023-0045, released April 25, 2023. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2023-0045
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0240
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 25, 2023

## 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

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.7-1 | [DEBIAN-CVE-2023-0045](https://patchblox.com/security/data/fix/linux/debian-cve-2023-0045.md) | Apr 25, 2023 |
| Linux | linux Debian 13.5 (trixie) | 6.1.7-1 | [DEBIAN-CVE-2023-0045](https://patchblox.com/security/data/fix/linux/debian-cve-2023-0045.md) | Apr 25, 2023 |
| Linux | linux Debian 14 | 6.1.7-1 | [DEBIAN-CVE-2023-0045](https://patchblox.com/security/data/fix/linux/debian-cve-2023-0045.md) | Apr 25, 2023 |

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