When plain IBRS is enabled (not enhanced IBRS), the logic in spectre_v2_user_select_mitigation() determines that STIBP is not needed. The IBRS bit implicitly protects against cross-thread branch target
injection. However, with legacy IBRS, the IBRS bit is cleared on returning to userspace for performance reasons which leaves userspace threads vulnerable to cross-thread branch target injection against which STIBP protects.
Platform | Package | Release Date | Advisory |
---|---|---|---|
Amazon Linux 1 | kernel | 2023-03-17 15:53 | ALAS-2023-1701 |
Amazon Linux 2 - Core | kernel | 2023-03-17 16:34 | ALAS2-2023-1987 |
Amazon Linux 2 - Kernel-5.10 Extra | kernel | 2023-03-17 16:46 | ALAS2KERNEL-5.10-2023-028 |
Amazon Linux 2 - Kernel-5.15 Extra | kernel | 2023-03-17 16:46 | ALAS2KERNEL-5.15-2023-015 |
Amazon Linux 2 - Kernel-5.4 Extra | kernel | 2023-03-17 16:45 | ALAS2KERNEL-5.4-2023-043 |
Amazon Linux 2023 | kernel | 2023-03-20 18:27 | ALAS2023-2023-138 |
Score Type | Score | Vector | |
---|---|---|---|
Amazon Linux | CVSSv3 | 5.6 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N |
NVD | CVSSv3 | 5.6 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N |