{"id":"CVE-2026-98719","summary":"KVM: SEV: Nullify \"have run CPUs\" mask pointer when freeing it","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Nullify \"have run CPUs\" mask pointer when freeing it\n\nNullify have_run_cpus when freeing the mask, particularly in the error path\nof __sev_guest_init(), so that KVM doesn't have to subtly use sev-\u003eactive\nto track whether or not the mask has been freed.  As pointed out by Sashiko,\nblindly freeing the mask in sev_vm_destroy() results in a double-free if\nthe mask is freed if __sev_guest_init() fails.\n\nThrow the logic in a helper as nullifying the pointer is frustratingly\ndifficult and weird due to have_run_cpus being a single-entry array when\nCPUMASK_OFFSTACK=n.  Deliberately don't use CPUMASK_VAR_NULL, as it's not\ndirectly assignable when the cpumask is on-stack, e.g. requires using a\nlocal variable and a memcpy(), which is beyond ridiculous.  Furthermore,\nwhile clearing the on-stack bitmask is an unnecessary and arguably unwanted\nside effect, KVM absolutely relies on '0' being the \"null\" value given that\nthe struct is zero-allocated.\n\nOpportunistically add an alloc() helper to pair with free(); there are just\nenough call sites to make doing so worthwhile.","modified":"2026-10-20T02:45:46.413849602Z","published":"2026-10-18T15:46:54.631Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98719.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0fbc7fec2242de6c3dcea6de55573c428e820173"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8abbc76120a74bfba1851bd97528099d715e45c6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b1de3ebf59507e0edacaa5cfa2225bc1869e1b63"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98719.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98719"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6aef7cf800098749ff5d660222efaf6e01e98c09"},{"fixed":"b1de3ebf59507e0edacaa5cfa2225bc1869e1b63"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"9784e5ca91b37b387f3f414af4340c54f7a63566"},{"fixed":"0fbc7fec2242de6c3dcea6de55573c428e820173"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"12c1f6e03f944e399bd2c88441dca5dc702b95a5"},{"fixed":"8abbc76120a74bfba1851bd97528099d715e45c6"}]}],"versions":["v6.18.55","v7.2.9"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98719.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.18.55"},{"fixed":"6.18.56"}]},{"type":"ECOSYSTEM","events":[{"introduced":"7.2.9"},{"fixed":"7.2.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98719.json"}}],"schema_version":"1.9.0"}