The do_get_mempolicy function in mm/mempolicy.c in the Linux kernel before 4.12.9 allows local users to cause a denial of service (use-after-free) or possibly have unspecified other impact via crafted system calls.
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.