CVE-2024-40984

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.