{"id":"CVE-2022-49559","summary":"KVM: x86: Drop WARNs that assert a triple fault never \"escapes\" from L2","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Drop WARNs that assert a triple fault never \"escapes\" from L2\n\nRemove WARNs that sanity check that KVM never lets a triple fault for L2\nescape and incorrectly end up in L1.  In normal operation, the sanity\ncheck is perfectly valid, but it incorrectly assumes that it's impossible\nfor userspace to induce KVM_REQ_TRIPLE_FAULT without bouncing through\nKVM_RUN (which guarantees kvm_check_nested_state() will see and handle\nthe triple fault).\n\nThe WARN can currently be triggered if userspace injects a machine check\nwhile L2 is active and CR4.MCE=0.  And a future fix to allow save/restore\nof KVM_REQ_TRIPLE_FAULT, e.g. so that a synthesized triple fault isn't\nlost on migration, will make it trivially easy for userspace to trigger\nthe WARN.\n\nClearing KVM_REQ_TRIPLE_FAULT when forcibly leaving guest mode is\ntempting, but wrong, especially if/when the request is saved/restored,\ne.g. if userspace restores events (including a triple fault) and then\nrestores nested state (which may forcibly leave guest mode).  Ignoring\nthe fact that KVM doesn't currently provide the necessary APIs, it's\nuserspace's responsibility to manage pending events during save/restore.\n\n  ------------[ cut here ]------------\n  WARNING: CPU: 7 PID: 1399 at arch/x86/kvm/vmx/nested.c:4522 nested_vmx_vmexit+0x7fe/0xd90 [kvm_intel]\n  Modules linked in: kvm_intel kvm irqbypass\n  CPU: 7 PID: 1399 Comm: state_test Not tainted 5.17.0-rc3+ #808\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n  RIP: 0010:nested_vmx_vmexit+0x7fe/0xd90 [kvm_intel]\n  Call Trace:\n   \u003cTASK\u003e\n   vmx_leave_nested+0x30/0x40 [kvm_intel]\n   vmx_set_nested_state+0xca/0x3e0 [kvm_intel]\n   kvm_arch_vcpu_ioctl+0xf49/0x13e0 [kvm]\n   kvm_vcpu_ioctl+0x4b9/0x660 [kvm]\n   __x64_sys_ioctl+0x83/0xb0\n   do_syscall_64+0x3b/0xc0\n   entry_SYSCALL_64_after_hwframe+0x44/0xae\n   \u003c/TASK\u003e\n  ---[ end trace 0000000000000000 ]---","modified":"2026-04-02T08:27:43.582115Z","published":"2025-02-26T02:14:05.059Z","related":["SUSE-SU-2025:1027-1","SUSE-SU-2025:1176-1","SUSE-SU-2025:1183-1","SUSE-SU-2025:1241-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49559.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/45846661d10422ce9e22da21f8277540b29eca22"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7de373c9b48229e428ecdb8fbde269c5a8617fd2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8d3a2aa0976f57320ba89baf9d57fb158dd0cd0d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f476a59d5c86c02a79eef893c6da86735f2977ac"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49559.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2022-49559"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"cb6a32c2b8777ad31a02e585584d869251a790e3"},{"fixed":"8d3a2aa0976f57320ba89baf9d57fb158dd0cd0d"},{"fixed":"f476a59d5c86c02a79eef893c6da86735f2977ac"},{"fixed":"7de373c9b48229e428ecdb8fbde269c5a8617fd2"},{"fixed":"45846661d10422ce9e22da21f8277540b29eca22"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49559.json"}}],"schema_version":"1.7.5"}