Description
In the Linux kernel, the following vulnerability has been resolved: arm64: Reserve an extra page for early kernel mapping The final part of [data, end) segment may overflow into the next page of init_pg_end[1] which is the gap page before early_init_stack[2]: [1] crash_arm64_v9.0.1> vtop ffffffed00601000 VIRTUAL PHYSICAL ffffffed00601000 83401000 PAGE DIRECTORY: ffffffecffd62000 PGD: ffffffecffd62da0 => 10000000833fb003 PMD: ffffff80033fb018 => 10000000833fe003 PTE: ffffff80033fe008 => 68000083401f03 PAGE: 83401000 PTE PHYSICAL FLAGS 68000083401f03 83401000 (VALID|SHARED|AF|NG|PXN|UXN) PAGE PHYSICAL MAPPING INDEX CNT FLAGS fffffffec00d0040 83401000 0 0 1 4000 reserved [2] ffffffed002c8000 (r) __pi__data ffffffed0054e000 (d) __pi___bss_start ffffffed005f5000 (b) __pi_init_pg_dir ffffffed005fe000 (b) __pi_init_pg_end ffffffed005ff000 (B) early_init_stack ffffffed00608000 (b) __pi__end For 4K pages, the early kernel mapping may use 2MB block entries but the kernel segments are only 64KB aligned. Segment boundaries that fall within a 2MB block therefore require a PTE table so that different attributes can be applied on either side of the boundary. KERNEL_SEGMENT_COUNT still correctly counts the five permanent kernel VMAs registered by declare_kernel_vmas(). However, since commit 5973a62efa34 ("arm64: map [_text, _stext) virtual address range non-executable+read-only"), the early mapper also maps [_text, _stext) separately from [_stext, _etext). This adds one more early-only split and can require one more page-table page than the existing EARLY_SEGMENT_EXTRA_PAGES allowance reserves. Increase the 4K-page early mapping allowance by one page to cover that additional split. [catalin.marinas@arm.com: rewrote part of the commit log] [catalin.marinas@arm.com: expanded the code comment]
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
fdd380a5950503a07aaaf74536a0c2f223475eb0 to < a4ff33053da0a34b14abb5c96dc5a48379e26fceaffected5973a62efa34c80c9a4e5eac1fca6f6209b902af to < dcb89deed40ba55ff7020061712fdabf098cc2ccaffected5973a62efa34c80c9a4e5eac1fca6f6209b902af to < 9fe9e3acaa14921b0cf0d6cc2de5b562499bf721affected5973a62efa34c80c9a4e5eac1fca6f6209b902af to < 4d8e74ad4585672489da6145b3328d415f50db82affected88025faf2aa08c7468d68d8cb31a53b55aae6ee0affected6.12.54 to < 6.12.91affected6.17.4 to < 6.18affected
Linux Linux
Default version status: affected
6.18affected0 to < 6.18unaffected6.12.91 to ≤ 6.12.*unaffected6.18.33 to ≤ 6.18.*unaffected7.0.10 to ≤ 7.0.*unaffected7.1 to ≤ *unaffected