Vulnerability CVE-2024-42131
Published: 2024-07-30

Description:
In the Linux kernel, the following vulnerability has been resolved:

mm: avoid overflows in dirty throttling logic

The dirty throttling logic is interspersed with assumptions that dirty
limits in PAGE_SIZE units fit into 32-bit (so that various multiplications
fit into 64-bits). If limits end up being larger, we will hit overflows,
possible divisions by 0 etc. Fix these problems by never allowing so
large dirty limits as they have dubious practical value anyway. For
dirty_bytes / dirty_background_bytes interfaces we can just refuse to set
so large limits. For dirty_ratio / dirty_background_ratio it isn't so
simple as the dirty limit is computed from the amount of available memory
which can change due to memory hotplug etc. So when converting dirty
limits from ratios to numbers of pages, we just don't allow the result to
exceed UINT_MAX.

This is root-only triggerable problem which occurs when the operator
sets dirty limits to >16 TB.

 References:
https://git.kernel.org/stable/c/7a49389771ae7666f4dc3426e2a4594bf23ae290
https://git.kernel.org/stable/c/a25e8536184516b55ef89ab91dd2eea429de28d2
https://git.kernel.org/stable/c/c83ed422c24f0d4b264f89291d4fabe285f80dbc
https://git.kernel.org/stable/c/bd16a7ee339aef3ee4c90cb23902afb6af379ea0
https://git.kernel.org/stable/c/8e0b5e7f2895eccef5c2a0018b589266f90c4805
https://git.kernel.org/stable/c/385d838df280eba6c8680f9777bfa0d0bfe7e8b2
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