CVE-2024-40984 — ACPICA: Revert "ACPICA: avoid Info: mapping multiple BARs. Your kernel is fine."

Affected: Linux, Siemens RUGGEDCOM RST2428P, Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 family, Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 family, Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

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

ACPICA: Revert "ACPICA: avoid Info: mapping multiple BARs. Your kernel is fine."

Undo the modifications made in commit d410ee5109a1 ("ACPICA: avoid "Info: mapping multiple BARs. Your kernel is fine.""). The initial purpose of this commit was to stop memory mappings for operation regions from overlapping page boundaries, as it can trigger warnings if different page attributes are present.

However, it was found that when this situation arises, mapping continues until the boundary's end, but there is still an attempt to read/write the entire length of the map, leading to a NULL pointer deference. For example, if a four-byte mapping request is made but only one byte is mapped because it hits the current page boundary's end, a four-byte read/write attempt is still made, resulting in a NULL pointer deference.

Instead, map the entire length, as the ACPI specification does not mandate that it must be within the same page boundary. It is permissible for it to be mapped across different regions.

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CVE-2024-40984 — ACPICA: Revert "ACPICA: avoid Info: mapping multiple BARs. Your kernel is fine."