Rust fixme 3

Description: Have you heard of Rust? Fix the syntax errors in this Rust file to print the flag!
Difficulty: Easy

🔎 Solution

After extracting the archive with tar -xvf fixme3.tar.gz, we obtain the following files: Cargo.toml, Cargo.lock, and src/main.rs.

Attempting to compile and run the project with cargo run results in the following error:

error[E0133]: call to unsafe function `std::slice::from_raw_parts` is unsafe and requires unsafe function or block

In Rust, certain operations are marked as unsafe because they have the potential to cause undefined behavior if not handled carefully. One such function is std::slice::from_raw_parts(ptr, len), which creates a slice from a raw pointer. This is inherently dangerous if:

The pointer ptr is invalid or null,
The length len is incorrect,
The memory region is not valid or accessible for the given range.

To ensure safety, Rust requires this function to be enclosed within an unsafe block. This signals to the compiler - and to the developer - that the caller takes full responsibility for ensuring memory safety.

To fix the issue, we modify line 31 of main.rs from:

let decrypted_slice = std::slice::from_raw_parts(decrypted_ptr, decrypted_len);

to:

let decrypted_slice = unsafe {
    std::slice::from_raw_parts(decrypted_ptr, decrypted_len)
};

Rebuilding and running the project again successfully yields the flag.

┌──(kali㉿kali)-[~/Desktop/pico-ctf/fixme3]
└─$ cargo run           
   Compiling rust_proj v0.1.0 (/home/kali/Desktop/pico-ctf/fixme3)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.35s
     Running `target/debug/rust_proj`
Using memory unsafe languages is a: PARTY FOUL! Here is your flag: picoCTF{n0w_y0uv3_f1x3d_1h3m_411}

🚩Flag

picoCTF{n0w_y0uv3_f1x3d_1h3m_411}

🔎 Solution​

🚩Flag​

🔎 Solution

🚩Flag