Kernel memory corruption via undersized pp_table allocation

Heap buffer overflow in Linux kernel amdgpu allows local users to corrupt kernel memory through the pp_table sysfs node. smu_sys_set_pp_table() retains an allocation sized for the first power table but later copies a larger table into that buffer without reallocating it. Local access to the AMD GPU power-table attribute is required; two writes can overwrite adjacent kernel heap data, disclose kernel memory, or crash or wedge the GPU.