{"id":"CVE-2026-64416","summary":"mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host\n\nlookup_swap_cgroup_id() passes swap_cgroup_ctrl[type].map to\n__swap_cgroup_id_lookup() without checking that the type was ever\nregistered via swap_cgroup_swapon().  On a swapless host every ctrl-\u003emap\nis NULL, so __swap_cgroup_id_lookup() dereferences NULL + a scaled\nswp_offset().\n\nSince commit bea67dcc5eea (\"mm: attempt to batch free swap entries for\nzap_pte_range()\"), zap_pte_range() -\u003e swap_pte_batch() calls\nlookup_swap_cgroup_id() on any non-present, non-none PTE that decodes as a\nreal swap entry, without first validating it against swap_info[].  A\nsingle PTE corrupted into a type-0 swap entry takes the host down at\nprocess exit.\n\nWe hit this in production on a swapless 6.12.58 host: ~1s of\n\"get_swap_device: Bad swap file entry 3f800204222bb\" (do_swap_page() being\ncorrectly defensive about the same entry) followed by\n\n  BUG: unable to handle page fault for address: 000003f800204220\n  RIP: 0010:lookup_swap_cgroup_id+0x2b/0x60\n  Call Trace:\n   swap_pte_batch+0xbf/0x230\n   zap_pte_range+0x4c8/0x780\n   unmap_page_range+0x190/0x3e0\n   exit_mmap+0xd9/0x3c0\n   do_exit+0x20c/0x4b0\n\nsyzbot has reported the identical stack.\n\nThe source of the PTE corruption is a separate bug; this change makes the\nteardown path as robust as the fault path already is.  Every other caller\nof lookup_swap_cgroup_id() is downstream of a get_swap_device() that has\nalready validated the entry, so the new branch is cold.","modified":"2026-07-27T04:03:19.376682673Z","published":"2026-07-25T08:50:55.997Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64416.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/63b02a9409cb5180398491b093e48bcb5315f5fb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6a4196d19f477524d2f92adca90fc1fbe9a0420a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/818416fef38759f23210de449663cd9d7e293d39"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b415c00bf23df577a4a95673d00ae76687bcc1d4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64416.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64416"},{"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":"bea67dcc5eea0f6a213897a59b9e644977cd07e6"},{"fixed":"818416fef38759f23210de449663cd9d7e293d39"},{"fixed":"b415c00bf23df577a4a95673d00ae76687bcc1d4"},{"fixed":"6a4196d19f477524d2f92adca90fc1fbe9a0420a"},{"fixed":"63b02a9409cb5180398491b093e48bcb5315f5fb"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64416.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.12.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64416.json"}}],"schema_version":"1.7.5"}