mm/mm_init: deferred_grow_zone(): fix out-of-range first_deferred_pfn

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-93227
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-24 16:17:18 UTC
Updated2026-10-19 10:17:13 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm/mm_init: deferred_grow_zone(): fix out-of-range first_deferred_pfn With CONFIG_DEFERRED_STRUCT_PAGE_INIT enabled, deferred_grow_zone() initializes struct pages early in boot to satisfy an allocation. With a large CMA reservation in place, the ranges deferred_init_memmap() finds may not add up to the allocation it was asked for, and the function ends up initializing the memory map of the entire zone and still falls short. That is fine in itself: the function accounts for it and leaves the caller to decide whether it now has enough memory. However, the update of pgdat->first_deferred_pfn that tracks where uninitialized memory map starts could overflow. If the node's RAM end is not aligned on PAGES_PER_SECTION boundaries and some deferred struct pages were initialized, pgdat->first_deferred_pfn would point past the end of the node's memory. deferred_init_memmap() later picks up from pgdat->first_deferred_pfn and hits a BUG_ON(), because it expects a pfn within its node. For example, when running a kernel with CONFIG_DEFERRED_STRUCT_PAGE_INIT=y and CONFIG_CMA=y using the following qemu command line qemu-system-x86_64 -enable-kvm -m 8032M -kernel bzImage \ -append "nokaslr cma=4768M@0x100000000" the kernel panics: kernel BUG at mm/mm_init.c:2131! CPU: 3 UID: 0 PID: 36 Comm: pgdatinit0 Not tainted 7.2.0-rc6 #1 RIP: 0010:deferred_init_memmap+0x1b8/0x1c0 RAX: 0000000000236000 R13: 0000000000238000 Call Trace: kthread+0xdf/0x120 ret_from_fork+0x187/0x250 Make sure that the update of pgdta->first_deferred_pfn does not overflow when the entire zone's (and therefore node's) memory map is initialized. [rppt: massaged the changelog]

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 45489d4f95802903ab35799b400b346fa4e13151 git Not specified
CNA Linux Linux affected 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 84339578c2d6936ac3a93cd1f0bbaa3468a988f2 git Not specified
CNA Linux Linux affected 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 97090500d776c3f6d08e857e3a0a7cf092999094 git Not specified
CNA Linux Linux affected 6.18 Not specified
CNA Linux Linux unaffected 6.18 semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/97090500d776c3f6d08e857e3a0a7cf092999094 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/45489d4f95802903ab35799b400b346fa4e13151 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/84339578c2d6936ac3a93cd1f0bbaa3468a988f2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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