The Linux kernel before 2.6.31-rc7 does not properly prevent mmap operations that target page zero and other low memory addresses, which allows local users to gain privileges by exploiting NULL pointer dereference vulnerabilities, related to (1) the default configuration of the allow_unconfined_mmap_low boolean in SELinux on Red Hat Enterprise Linux (RHEL) 5, (2) an error that causes allow_unconfined_mmap_low to be ignored in the unconfined_t domain, (3) lack of a requirement for the CAP_SYS_RAWIO capability for these mmap operations, and (4) interaction between the mmap_min_addr protection mechanism and certain application programs.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.