{"id":"CVE-2026-64416","state":"PUBLISHED","title":"mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host","description":"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->map\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() -> 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.","publishedAt":"2026-07-25T08:50:55.997Z","updatedAt":"2026-08-17T04:55:15.618Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"bea67dcc5eea0f6a213897a59b9e644977cd07e6","status":"affected","lessThan":"818416fef38759f23210de449663cd9d7e293d39","versionType":"git"},{"version":"bea67dcc5eea0f6a213897a59b9e644977cd07e6","status":"affected","lessThan":"b415c00bf23df577a4a95673d00ae76687bcc1d4","versionType":"git"},{"version":"bea67dcc5eea0f6a213897a59b9e644977cd07e6","status":"affected","lessThan":"6a4196d19f477524d2f92adca90fc1fbe9a0420a","versionType":"git"},{"version":"bea67dcc5eea0f6a213897a59b9e644977cd07e6","status":"affected","lessThan":"63b02a9409cb5180398491b093e48bcb5315f5fb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/swap_cgroup.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/swap_cgroup.c"]}],"references":["https://git.kernel.org/stable/c/818416fef38759f23210de449663cd9d7e293d39","https://git.kernel.org/stable/c/b415c00bf23df577a4a95673d00ae76687bcc1d4","https://git.kernel.org/stable/c/6a4196d19f477524d2f92adca90fc1fbe9a0420a","https://git.kernel.org/stable/c/63b02a9409cb5180398491b093e48bcb5315f5fb"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64416.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64416","state":"PUBLISHED","datePublished":"2026-07-25T08:50:55.997Z","dateUpdated":"2026-08-17T04:55:15.618Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.786Z"},"containers":{"cna":{"title":"mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host","descriptions":[{"lang":"en","value":"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->map\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() -> 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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"bea67dcc5eea0f6a213897a59b9e644977cd07e6","status":"affected","lessThan":"818416fef38759f23210de449663cd9d7e293d39","versionType":"git"},{"version":"bea67dcc5eea0f6a213897a59b9e644977cd07e6","status":"affected","lessThan":"b415c00bf23df577a4a95673d00ae76687bcc1d4","versionType":"git"},{"version":"bea67dcc5eea0f6a213897a59b9e644977cd07e6","status":"affected","lessThan":"6a4196d19f477524d2f92adca90fc1fbe9a0420a","versionType":"git"},{"version":"bea67dcc5eea0f6a213897a59b9e644977cd07e6","status":"affected","lessThan":"63b02a9409cb5180398491b093e48bcb5315f5fb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/swap_cgroup.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/swap_cgroup.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/818416fef38759f23210de449663cd9d7e293d39"},{"url":"https://git.kernel.org/stable/c/b415c00bf23df577a4a95673d00ae76687bcc1d4"},{"url":"https://git.kernel.org/stable/c/6a4196d19f477524d2f92adca90fc1fbe9a0420a"},{"url":"https://git.kernel.org/stable/c/63b02a9409cb5180398491b093e48bcb5315f5fb"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:55:15.618Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}