CVE-2024-57945: riscv: mm: Fix the out of bound issue of vmemmap address

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-01-21 · updated 2026-08-04
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: riscv: mm: Fix the out of bound issue of vmemmap address In sparse vmemmap model, the virtual address of vmemmap is calculated as: ((struct page *)VMEMMAP_START - (phys_ram_base >> PAGE_SHIFT)). And the struct page's va can be calculated with an offset: (vmemmap + (pfn)). However, when initializing struct pages, kernel actually starts from the first page from the same section that phys_ram_base belongs to. If the first page's physical address is not (phys_ram_base >> PAGE_SHIFT), then we get an va below VMEMMAP_START when calculating va for it's struct page. For example, if phys_ram_base starts from 0x82000000 with pfn 0x82000, the first page in the same section is actually pfn 0x80000. During init_unavailable_range(), we will initialize struct page for pfn 0x80000 with virtual address ((struct page *)VMEMMAP_START - 0x2000), which is below VMEMMAP_START as well as PCI_IO_END. This commit fixes this bug by introducing a new variable 'vmemmap_start_pfn' which is aligned with memory section size and using it to calculate vmemmap address instead of phys_ram_base.

Affected products

Linux kernel: from 5.10.212 before 5.11; from 5.15.151 before 5.16; from 6.1.81 before 6.1.140; from 6.6.21 before 6.6.72; from 6.7.9 before 6.8; from 6.8.1 before 6.12.10 — fixed in 5.11, 5.16, 6.1.140, 6.12.10, 6.6.72, 6.8

How to fix

Upgrade to a fixed version: Linux kernel 5.11, 5.16, 6.1.140, 6.12.10. Check the vendor advisory for mitigations.

References

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