In the Linux kernel, the following vulnerability has been resolved: arm_mpam: guard MBWU state...

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

arm_mpam: guard MBWU state before adding it to garbage

__destroy_component_cfg() adds each RIS mbwu_state object to the MPAM garbage list when destroying component configuration.

However, mbwu_state is allocated per RIS and only for RISes with MBWU monitors. A component can therefore have comp->cfg allocated while some RISes still have ris->mbwu_state set to NULL.

Passing a NULL mbwu_state to add_to_garbage() dereferences the NULL pointer inside the macro.

Skip RISes that do not have an mbwu_state object before adding them to the garbage list.