{"id":"CVE-2026-93227","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/mm_init: deferred_grow_zone(): fix out-of-range first_deferred_pfn\n\nWith CONFIG_DEFERRED_STRUCT_PAGE_INIT enabled, deferred_grow_zone()\ninitializes struct pages earl…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/mm_init: deferred_grow_zone(): fix out-of-range first_deferred_pfn\n\nWith CONFIG_DEFERRED_STRUCT_PAGE_INIT enabled, deferred_grow_zone()\ninitializes struct pages earl…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 < 45489d4f95802903ab35799b400b346fa4e13151","Linux >= 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 < 84339578c2d6936ac3a93cd1f0bbaa3468a988f2","Linux >= 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 < 97090500d776c3f6d08e857e3a0a7cf092999094","Linux 6.18"],"published":"2026-09-24","updated":"2026-09-24","sourceUpdated":"2026-09-24T16:17:18.130","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-93227","references":[{"url":"https://git.kernel.org/stable/c/45489d4f95802903ab35799b400b346fa4e13151","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/84339578c2d6936ac3a93cd1f0bbaa3468a988f2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/97090500d776c3f6d08e857e3a0a7cf092999094","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-09-24T15:45:56.663Z","slug":"CVE-2026-93227","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nmm/mm_init: deferred_grow_zone(): fix out-of-range first_deferred_pfn\n\nWith CONFIG_DEFERRED_STRUCT_PAGE_INIT enabled, deferred_grow_zone()\ninitializes struct pages early in boot to satisfy an allocation.\n\nWith a large CMA reservation in place, the ranges deferred_init_memmap()\nfinds may not add up to the allocation it was asked for, and the function\nends up initializing the memory map of the entire zone and still falls\nshort.\n\nThat is fine in itself: the function accounts for it and leaves the\ncaller to decide whether it now has enough memory.\n\nHowever, the update of pgdat->first_deferred_pfn that tracks where\nuninitialized memory map starts could overflow.\n\nIf the node's RAM end is not aligned on PAGES_PER_SECTION boundaries and\nsome deferred struct pages were initialized, pgdat->first_deferred_pfn\nwould point past the end of the node's memory.\n\ndeferred_init_memmap() later picks up from pgdat->first_deferred_pfn and\nhits a BUG_ON(), because it expects a pfn within its node.\n\nFor example, when running a kernel with CONFIG_DEFERRED_STRUCT_PAGE_INIT=y\nand CONFIG_CMA=y using the following qemu command line\n\n  qemu-system-x86_64 -enable-kvm -m 8032M -kernel bzImage \\\n      -append \"nokaslr cma=4768M@0x100000000\"\n\nthe kernel panics:\n\n  kernel BUG at mm/mm_init.c:2131!\n  CPU: 3 UID: 0 PID: 36 Comm: pgdatinit0 Not tainted 7.2.0-rc6 #1\n  RIP: 0010:deferred_init_memmap+0x1b8/0x1c0\n  RAX: 0000000000236000 R13: 0000000000238000\n  Call Trace:\n   kthread+0xdf/0x120\n   ret_from_fork+0x187/0x250\n\nMake sure that the update of pgdta->first_deferred_pfn does not overflow\nwhen the entire zone's (and therefore node's) memory map is initialized.\n\n[rppt: massaged the changelog]\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}