Use-after-free vulnerability in mm/mprotect.c in the Linux kernel before 2.6.37-rc2 allows local users to cause a denial of service via vectors involving an mprotect system call.
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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.