CVE-2023-0045 Incorrect indirect branch prediction barrier in the Linux Kernel

2023-04-2522:44:57

CWE-610

Google

www.cve.org

cve-2023-0045

linux kernel

indirect branch prediction

syscall

vulnerability

update

patch

4.7 Medium

CVSS3

Attack Vector

LOCAL

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

NONE

Availability Impact

NONE

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

7.8 High

AI Score

Confidence

High

0.002 Low

EPSS

Percentile

57.9%

JSON

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

CNA Affected

[
  {
    "defaultStatus": "unaffected",
    "packageName": "kernel",
    "product": "Linux Kernel",
    "repo": "https://git.kernel.org",
    "vendor": "Linux",
    "versions": [
      {
        "lessThan": "a664ec9158eeddd75121d39c9a0758016097fa96",
        "status": "affected",
        "version": "9137bb27e60e",
        "versionType": "git"
      }
    ]
  }
]