{"id":"CVE-2026-89923","summary":"KVM: s390: Free guest debug data on vcpu destroy","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: Free guest debug data on vcpu destroy\n\nkvm_s390_clear_bp_data() is only called from\nkvm_arch_vcpu_ioctl_set_guest_debug(), i.e. when user space changes or\ndisables debugging. A vCPU that is destroyed while hardware breakpoints\nare still armed - the normal case when the VMM just exits or crashes -\nleaks hw_bp_info, hw_wp_info and all old_data buffers, since generic KVM\nfrees the vCPU right after kvm_arch_vcpu_destroy().\n\nThat is bounded by MAX_BP_COUNT entries, so roughly 8 KiB per vCPU, but\nit is unbounded over VM lifetimes. The allocations are\nGFP_KERNEL_ACCOUNT, so the charge also outlives the exiting process and\npins dying memcgs.\n\nFix by clearing the debug data on vCPU destruction. Calling it\nunconditionally is fine: struct kvm_vcpu is zero allocated, so for a vCPU\nthat never enabled debugging the counters are 0 and the pointers NULL.","modified":"2026-09-18T03:48:34.148644707Z","published":"2026-09-16T10:32:16.765Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89923.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/053f2068cf9b0654b651fed5ad7649d3deb982bf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/544a5a665019cef394ce8bda97fa7a2cab253781"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6c996b12bbe4a6023076e8eee3cfaf2cc99db76c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b5acacfdb8966abff91836c1c5bd7da59d8a526e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d6280fc540d8f4653c9b54a78cb747e128070f5e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e4d8b7f176b976474e0800ba71ee2dfa3ce263c9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e7f698b09d4a7c36b299acf680fc50fe868e2bcd"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89923.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89923"},{"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":"27291e2165b6de70c476b7b675308113edd69a60"},{"fixed":"053f2068cf9b0654b651fed5ad7649d3deb982bf"},{"fixed":"6c996b12bbe4a6023076e8eee3cfaf2cc99db76c"},{"fixed":"d6280fc540d8f4653c9b54a78cb747e128070f5e"},{"fixed":"544a5a665019cef394ce8bda97fa7a2cab253781"},{"fixed":"9a32c4c6a6c23b7f5bf765eb5b83ba7f64a8ec63"},{"fixed":"b5acacfdb8966abff91836c1c5bd7da59d8a526e"},{"fixed":"e4d8b7f176b976474e0800ba71ee2dfa3ce263c9"},{"fixed":"e7f698b09d4a7c36b299acf680fc50fe868e2bcd"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89923.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.16.0"},{"fixed":"5.10.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89923.json"}}],"schema_version":"1.9.0"}