{"id":"CVE-2026-72292","summary":"KVM: s390: Initialize KVM_S390_GET_CMMA_BITS memory","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: Initialize KVM_S390_GET_CMMA_BITS memory\n\nkvm_s390_get_cmma_bits() allocates its output buffer with vmalloc(),\nwhich does not zero the returned pages:\n\n\tvalues = vmalloc(args-\u003ecount);\n\nIn the non-peek (migration) path, dat_get_cmma() reports a byte count\nspanning from the first to the last dirty page, but __dat_get_cmma_pte()\nwrites values[gfn - start] only for pages whose CMMA dirty bit is set.\nThe walk uses DAT_WALK_IGN_HOLES, so clean and unmapped pages that lie\nbetween two dirty pages within the reported span are visited but never\nstore their byte.  Those gaps (up to KVM_S390_MAX_BIT_DISTANCE pages\neach) stay uninitialized yet fall inside [0, count) and are copied out\nby copy_to_user(), disclosing stale kernel memory to user space.\n\nBefore the switch to the new gmap implementation the buffer was fully\npopulated for every gfn in the span, so no uninitialized bytes were\nexposed; the dirty-only walk introduced the leak.\n\nUse vzalloc() so the gaps read back as zero.","modified":"2026-08-18T03:30:54.213454052Z","published":"2026-08-15T05:55:13.248Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72292.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/a4a19941ccb2164edc3491faa5ac5df82e94b363"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c7dda3d0f869dc97223448a06c9a2e5235928e48"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72292.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72292"},{"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":"e38c884df92119d96f652d51f82661dd2fc0b885"},{"fixed":"a4a19941ccb2164edc3491faa5ac5df82e94b363"},{"fixed":"c7dda3d0f869dc97223448a06c9a2e5235928e48"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72292.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.0.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72292.json"}}],"schema_version":"1.9.0"}