BPF verifier
also: eBPF verifier, BPF safety verifier
A kernel component that validates eBPF programs before execution to ensure they are safe and won't crash or compromise system stability. It checks for memory access violations, infinite loops, and other dangerous operations.
The BPF verifier is a sophisticated static analysis engine in the Linux kernel that examines every eBPF (extended Berkeley Packet Filter) program before it runs. It walks through all possible execution paths to catch unsafe operations at load time rather than letting them fail at runtime.
The verifier performs multiple checks including: confirming that memory accesses are within bounds, detecting infinite loops or unreachable code, validating function calls, and ensuring all variables are properly initialized. For example, when loading a BPF program that reads from a network packet buffer, the verifier confirms the program won't read past the buffer's end.
Without the verifier, unprivileged or buggy eBPF programs could panic the kernel or leak sensitive memory. By rejecting unsafe programs during loading, the verifier allows the kernel to safely run eBPF in contexts like tracing, networking, and security monitoring while maintaining system integrity.