Description
In the Linux kernel, the following vulnerability has been resolved: x86/vmscape: Add conditional IBPB mitigation VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM from a malicious guest. Userspace can additionally be protected by flushing the branch predictors after a VMexit. Since it is the userspace that consumes the poisoned branch predictors, conditionally issue an IBPB after a VMexit and before returning to userspace. Workloads that frequently switch between hypervisor and userspace will incur the most overhead from the new IBPB. This new IBPB is not integrated with the existing IBPB sites. For instance, a task can use the existing speculation control prctl() to get an IBPB at context switch time. With this implementation, the IBPB is doubled up: one at context switch and another before running userspace. The intent is to integrate and optimize these cases post-embargo. [ dhansen: elaborate on suboptimal IBPB solution ]
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
15d45071523d89b3fb7372e2135fbd72f6af9506 to < ac60717f9a8d21c58617d0b34274babf24135835affected15d45071523d89b3fb7372e2135fbd72f6af9506 to < c08192b5d6730a914dee6175bc71092ee6a65f14affected15d45071523d89b3fb7372e2135fbd72f6af9506 to < d5490dfa35427a2967e00a4c7a1b95fdbc8ede34affected15d45071523d89b3fb7372e2135fbd72f6af9506 to < 2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6eaffected15d45071523d89b3fb7372e2135fbd72f6af9506 to < 15006289e5c38b2a830e1fba221977a27598176caffected15d45071523d89b3fb7372e2135fbd72f6af9506 to < 893387c18612bb452336a5881da0d015a7e8f4a2affected15d45071523d89b3fb7372e2135fbd72f6af9506 to < f866eef8d1c65504d30923c3f14082ad294d0e6daffected15d45071523d89b3fb7372e2135fbd72f6af9506 to < 34e5667041050711a947e260fc9ebebe08bddee5affected15d45071523d89b3fb7372e2135fbd72f6af9506 to < d7ddc93392e4a7ffcccc86edf6ef3e64c778db52affected15d45071523d89b3fb7372e2135fbd72f6af9506 to < 459274c77b37ac63b78c928b4b4e748d1f9d05c8affected15d45071523d89b3fb7372e2135fbd72f6af9506 to < 510603f504796c3535f67f55fb0b124a303b44c8affected15d45071523d89b3fb7372e2135fbd72f6af9506 to < 9c23a90648e831d611152ac08dbcd1283d405e7faffected15d45071523d89b3fb7372e2135fbd72f6af9506 to < 2f8f173413f1cbf52660d04df92d0069c4306d25affectedc51f1e5f57cca88d8d5894b6fad1638f643a99d0affected4b3870c343a82cd2df7192cc5149c87205dcc611affected3.16.57 to < 3.17affected4.4.168 to < 4.5affected
Linux Linux
Default version status: affected
4.16affected0 to < 4.16unaffected5.10.244 to ≤ 5.10.*unaffected5.15.193 to ≤ 5.15.*unaffected6.1.152 to ≤ 6.1.*unaffected6.6.106 to ≤ 6.6.*unaffected6.12.47 to ≤ 6.12.*unaffected6.16.7 to ≤ 6.16.*unaffected6.17 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/ac60717f9a8d21c58617d0b34274babf24135835 ↗
- https://git.kernel.org/stable/c/c08192b5d6730a914dee6175bc71092ee6a65f14 ↗
- https://git.kernel.org/stable/c/d5490dfa35427a2967e00a4c7a1b95fdbc8ede34 ↗
- https://git.kernel.org/stable/c/2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e ↗
- https://git.kernel.org/stable/c/15006289e5c38b2a830e1fba221977a27598176c ↗
- https://git.kernel.org/stable/c/893387c18612bb452336a5881da0d015a7e8f4a2 ↗
- https://git.kernel.org/stable/c/f866eef8d1c65504d30923c3f14082ad294d0e6d ↗
- https://git.kernel.org/stable/c/34e5667041050711a947e260fc9ebebe08bddee5 ↗
- https://git.kernel.org/stable/c/d7ddc93392e4a7ffcccc86edf6ef3e64c778db52 ↗
- https://git.kernel.org/stable/c/459274c77b37ac63b78c928b4b4e748d1f9d05c8 ↗
- https://git.kernel.org/stable/c/510603f504796c3535f67f55fb0b124a303b44c8 ↗
- https://git.kernel.org/stable/c/9c23a90648e831d611152ac08dbcd1283d405e7f ↗
- https://git.kernel.org/stable/c/2f8f173413f1cbf52660d04df92d0069c4306d25 ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html ↗
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html ↗
- http://www.openwall.com/lists/oss-security/2025/11/14/3 ↗
- http://www.openwall.com/lists/oss-security/2025/11/14/4 ↗
- http://www.openwall.com/lists/oss-security/2025/11/14/6 ↗
- http://www.openwall.com/lists/oss-security/2025/11/17/2 ↗
- http://www.openwall.com/lists/oss-security/2025/11/17/3 ↗
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html ↗