CVE-2024-57881: mm/page_alloc: don't call pfn_to_page() on possibly non-existent PFN in split_large_buddy()
Description
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.
Classification
CVE ID: CVE-2024-57881
Affected Products
Vendor: Linux
Product: Linux
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.04% (probability of being exploited)
EPSS Percentile: 11.47% (scored less or equal to compared to others)
EPSS Date: 2025-02-09 (when was this score calculated)
References
https://git.kernel.org/stable/c/4234ca9884bcae9e48ed38652d91696ad5cd591dhttps://git.kernel.org/stable/c/faeec8e23c10bd30e8aa759a2eb3018dae00f924