CVE-2024-57945

/// Technical 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 introdu

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References