Race Condition in ioctl_file_dedupe_range (Linux Kernel <= 4.7)

This repository contains multiple C source files and supporting documentation for exploiting the double-fetch vulnerability (CVE-2016-6516) in the Linux kernel's file deduplication ioctl (FIDEDUPERANGE). The main exploit logic is found in 'exploit.c', which is an annotated and optimized version of the original proof-of-concept by Scott Bauer (whose code is in 'Scott Bauer/doublefetch.c'). The exploit works by creating a race condition between two threads: one thread repeatedly changes the 'dest_count' field of a 'file_dedupe_range' structure, while the other triggers the FIDEDUPERANGE ioctl. This can cause the kernel to fetch inconsistent values, potentially leading to memory corruption or privilege escalation. The repository also includes kernel source files ('ioctl.c', 'read_write.c') for reference, and a 'cmd.txt' file with instructions for setting up a vulnerable kernel environment. The exploit is a proof-of-concept and does not provide a direct shell or privilege escalation payload, but demonstrates the vulnerability's exploitability. The attack vector is local, requiring the attacker to execute code on the target system. Fingerprintable endpoints include the file paths used for the deduplication operation.