Executive brief
A technical issue was identified in the Linux kernel's memory management for ARM64 systems. During the early startup phase, the system could potentially run out of reserved memory pages used to map the kernel into memory, leading to an overflow into adjacent memory areas. While primarily a stability concern during the boot process, it could lead to unpredictable system behavior or crashes on affected hardware.
Technical details
A vulnerability in the arm64 early kernel mapping logic occurs when using 4K pages. The early mapper maps the [_text, _stext) virtual address range separately from [_stext, _etext), creating an additional segment split. Because kernel segments are 64KB aligned but 2MB block entries may be used, this split can require more page-table pages than the EARLY_SEGMENT_EXTRA_PAGES constant originally reserved. This results in the final part of the [data, end) segment potentially overflowing into the gap page before the early initialization stack. The fix increases the reservation allowance by one page to accommodate the additional split.
Affected products
- Linux Linux Kernel arm64 architecture
Timeline
- 2026-04-30: disclosed: Initial patch authored
- 2026-06-26: advisory: CVE-2026-53288 published