{"api_version":"1","generated_at":"2026-10-04T23:02:23+00:00","cve":"CVE-2026-93253","urls":{"html":"https://cve.report/CVE-2026-93253","api":"https://cve.report/api/cve/CVE-2026-93253.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-93253","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-93253"},"summary":{"title":"sched/isolation: Defer freeing of cpumask memblock memory to initcall","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/isolation: Defer freeing of cpumask memblock memory to initcall\n\nWhen testing a linux-next kernel with commit 59bd1d914bb5 (\"memblock:\nwarn when freeing reserved memory before memory map is initialized\"),\nthe following warning was hit when there was a \"nohz_full\" kernel boot\nparameter.\n\n  Cannot free reserved memory because of deferred initialization of the memory map\n  WARNING: mm/memblock.c:904 at __free_reserved_area+0xde/0xf0, CPU#0: swapper/0/0\n    :\n  Call Trace:\n   <TASK>\n   memblock_phys_free+0xcb/0x100\n   housekeeping_init+0x14c/0x170\n   start_kernel+0x207/0x450\n   x86_64_start_reservations+0x24/0x30\n   x86_64_start_kernel+0xda/0xe0\n   common_startup_64+0x13e/0x141\n   </TASK>\n\nIOW, we shouldn't free memblock allocated memory so early\nin the boot process when memory map isn't fully initialized in\ndeferred_init_memmap().\n\nFix it by saving the housekeeping cpumask memblock memory to be\nfreed into a llist free list in housekeeping_init() and add a new\nhousekeeping_late_init() helper to defer the actual freeing of memblock\nmemory to when initcall's are being processed. The cpumask memblock\nmemory is treated as a llist_node with the size of a \"long\" type which\nis also smallest cpumask size that can be allocated.\n\nThe non-atomic version of the llist APIs are used as there is no\ncontention.\n\nThis commit depends on the presence of commit 7c2eee9c1367 (\"memblock:\ndon't touch memblock arrays when memblock_free() is called late\")\nto prevent a KASAN UAF bug report [1].\n\n [1] https://lore.kernel.org/lkml/20260505051821.1107133-1-longman@redhat.com/","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-24 16:17:21","updated_at":"2026-09-24 16:17:21"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/811fdac2d1bdf0b0d3fda262aac288ddd13a1422","name":"https://git.kernel.org/stable/c/811fdac2d1bdf0b0d3fda262aac288ddd13a1422","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2b58c749b8c5244e259a0230bc57b10b010dc545","name":"https://git.kernel.org/stable/c/2b58c749b8c5244e259a0230bc57b10b010dc545","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-93253","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93253","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 27c3a5967f054ab666704cb28f2aeb18ca07cab7 811fdac2d1bdf0b0d3fda262aac288ddd13a1422 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 27c3a5967f054ab666704cb28f2aeb18ca07cab7 2b58c749b8c5244e259a0230bc57b10b010dc545 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.0","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["kernel/sched/isolation.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"811fdac2d1bdf0b0d3fda262aac288ddd13a1422","status":"affected","version":"27c3a5967f054ab666704cb28f2aeb18ca07cab7","versionType":"git"},{"lessThan":"2b58c749b8c5244e259a0230bc57b10b010dc545","status":"affected","version":"27c3a5967f054ab666704cb28f2aeb18ca07cab7","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["kernel/sched/isolation.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.0"},{"lessThan":"7.0","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"7.0","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"7.0","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/isolation: Defer freeing of cpumask memblock memory to initcall\n\nWhen testing a linux-next kernel with commit 59bd1d914bb5 (\"memblock:\nwarn when freeing reserved memory before memory map is initialized\"),\nthe following warning was hit when there was a \"nohz_full\" kernel boot\nparameter.\n\n  Cannot free reserved memory because of deferred initialization of the memory map\n  WARNING: mm/memblock.c:904 at __free_reserved_area+0xde/0xf0, CPU#0: swapper/0/0\n    :\n  Call Trace:\n   <TASK>\n   memblock_phys_free+0xcb/0x100\n   housekeeping_init+0x14c/0x170\n   start_kernel+0x207/0x450\n   x86_64_start_reservations+0x24/0x30\n   x86_64_start_kernel+0xda/0xe0\n   common_startup_64+0x13e/0x141\n   </TASK>\n\nIOW, we shouldn't free memblock allocated memory so early\nin the boot process when memory map isn't fully initialized in\ndeferred_init_memmap().\n\nFix it by saving the housekeeping cpumask memblock memory to be\nfreed into a llist free list in housekeeping_init() and add a new\nhousekeeping_late_init() helper to defer the actual freeing of memblock\nmemory to when initcall's are being processed. The cpumask memblock\nmemory is treated as a llist_node with the size of a \"long\" type which\nis also smallest cpumask size that can be allocated.\n\nThe non-atomic version of the llist APIs are used as there is no\ncontention.\n\nThis commit depends on the presence of commit 7c2eee9c1367 (\"memblock:\ndon't touch memblock arrays when memblock_free() is called late\")\nto prevent a KASAN UAF bug report [1].\n\n [1] https://lore.kernel.org/lkml/20260505051821.1107133-1-longman@redhat.com/"}],"providerMetadata":{"dateUpdated":"2026-09-24T15:51:29.259Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/811fdac2d1bdf0b0d3fda262aac288ddd13a1422"},{"url":"https://git.kernel.org/stable/c/2b58c749b8c5244e259a0230bc57b10b010dc545"}],"title":"sched/isolation: Defer freeing of cpumask memblock memory to initcall","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-93253","datePublished":"2026-09-24T15:51:29.259Z","dateReserved":"2026-09-17T16:02:15.096Z","dateUpdated":"2026-09-24T15:51:29.259Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-24 16:17:21","lastModifiedDate":"2026-09-24 16:17:21","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"93253","Ordinal":"1","Title":"sched/isolation: Defer freeing of cpumask memblock memory to ini","CVE":"CVE-2026-93253","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"93253","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched/isolation: Defer freeing of cpumask memblock memory to initcall\n\nWhen testing a linux-next kernel with commit 59bd1d914bb5 (\"memblock:\nwarn when freeing reserved memory before memory map is initialized\"),\nthe following warning was hit when there was a \"nohz_full\" kernel boot\nparameter.\n\n  Cannot free reserved memory because of deferred initialization of the memory map\n  WARNING: mm/memblock.c:904 at __free_reserved_area+0xde/0xf0, CPU#0: swapper/0/0\n    :\n  Call Trace:\n   <TASK>\n   memblock_phys_free+0xcb/0x100\n   housekeeping_init+0x14c/0x170\n   start_kernel+0x207/0x450\n   x86_64_start_reservations+0x24/0x30\n   x86_64_start_kernel+0xda/0xe0\n   common_startup_64+0x13e/0x141\n   </TASK>\n\nIOW, we shouldn't free memblock allocated memory so early\nin the boot process when memory map isn't fully initialized in\ndeferred_init_memmap().\n\nFix it by saving the housekeeping cpumask memblock memory to be\nfreed into a llist free list in housekeeping_init() and add a new\nhousekeeping_late_init() helper to defer the actual freeing of memblock\nmemory to when initcall's are being processed. The cpumask memblock\nmemory is treated as a llist_node with the size of a \"long\" type which\nis also smallest cpumask size that can be allocated.\n\nThe non-atomic version of the llist APIs are used as there is no\ncontention.\n\nThis commit depends on the presence of commit 7c2eee9c1367 (\"memblock:\ndon't touch memblock arrays when memblock_free() is called late\")\nto prevent a KASAN UAF bug report [1].\n\n [1] https://lore.kernel.org/lkml/20260505051821.1107133-1-longman@redhat.com/","Type":"Description","Title":"sched/isolation: Defer freeing of cpumask memblock memory to ini"}]}}}