Unsound usages of unsafe implementation about c_void

Hi, I am scanning this crate in the latest version using my own static analyzer tool.

Unsafe pointer conversion is found at: src/netmap_user.rs:16

pub unsafe fn _NETMAP_OFFSET<T, U>(ptr: *mut U, offset: isize) -> *mut T {
    ((ptr as *mut c_char).offset(offset) as *mut c_void) as *mut T
}

This unsound implementation would create memory issues such as overflow, underflow, or misalignment, since the type is converted to c_void (1 byte, 8 bits). The attacker can manipulate the argument offset associated with the c_void pointer with a large value, as well as T and U, which can lead to a buffer overflow bug.

This would cause undefined behaviors in Rust. Adversaries can manipulate the associated arguments to cause memory safety bugs. I am reporting this issue for your attention.

Start with src/netmap_user.rs:16 and the _NETMAP_OFFSET function, then review Rust’s undefined-behavior requirements for raw-pointer offset, alignment, and bounds. Validate the static-analyzer report against the function’s callers and determine whether the reported conversion can produce the claimed memory-safety issue. Done means the finding has a clear resolution and appropriate verification.