CVE-2024-36891

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

mapletree: fix masemptyarearev() null pointer dereference

Currently the code calls masstart() followed by masdataend() if the maple state is MASTART, but masstart() may return with the maple state node == NULL. This will lead to a null pointer dereference when checking information in the NULL node, which is done in masdata_end().

Avoid setting the offset if there is no node by waiting until after the maple state is checked for an empty or single entry state.

A user could trigger the events to cause a kernel oops by unmapping all vmas to produce an empty maple tree, then mapping a vma that would cause the scenario described above.