Bug 2337151 (CVE-2024-57881)

Summary: CVE-2024-57881 kernel: mm/page_alloc: don't call pfn_to_page() on possibly non-existent PFN in split_large_buddy()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-01-11 16:01:13 UTC 
In the Linux kernel, the following vulnerability has been resolved:

mm/page_alloc: don't call pfn_to_page() on possibly non-existent PFN in split_large_buddy()

In split_large_buddy(), we might call pfn_to_page() on a PFN that might
not exist.  In corner cases, such as when freeing the highest pageblock in
the last memory section, this could result with CONFIG_SPARSEMEM &&
!CONFIG_SPARSEMEM_EXTREME in __pfn_to_section() returning NULL and and
__section_mem_map_addr() dereferencing that NULL pointer.

Let's fix it, and avoid doing a pfn_to_page() call for the first
iteration, where we already have the page.

So far this was found by code inspection, but let's just CC stable as the
fix is easy.
Comment 1 Avinash Hanwate 2025-01-13 05:23:22 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025011146-CVE-2024-57881-7516@gregkh/T