This module exploits a user-after-free vulnerability in the Linux Kernel. When bpf(BPF_PROG_LOAD, ...) was invoked with a BPF program whose bytecode references a non-map file descriptor as a map file descriptor, the error handling code called fdput() twice instead of once (in __bpf_map_get() and in replace_map_fd_with_map_ptr()). If the file descriptor table of the current task is shared, this causes f_count to be decremented too much, allowing the struct file to be freed while it is still in use (use-after-free). This can be exploited to gain root privileges by an unprivileged user. WARNING: This is an early release module. This is not the final version of this module. It is a pre-released version in order to deliver a module as quickly as possible to our customers that may be useful in some situations. Since this module is not the final version it may contain bugs or have limited functionality and may not have complete or accurate documentation.
Thursday, May 5, 2016 - 19:00