Potential fix for code scanning alert no. 5: Uncontrolled command line

[davewichers]

Potential fix for https://github.com/aspectsecurity/TestCodeQL/security/code-scanning/5

In general, to fix uncontrolled command line use, avoid passing raw user input into Runtime.exec or similar APIs. Prefer either (1) not executing a system command at all and handling the operation in Java, or (2) if a system command is necessary, use a fixed command or a whitelisted set of arguments and pass them as separate parameters (string array) to exec, after validating that user input matches expected safe patterns.

For this specific code, the simplest safe change that preserves apparent functionality is to (a) avoid concatenating bar directly into the command string, and (b) validate or neutralize bar before using it. Since the intended command appears to be an echo of user input, we can instead pass cmd and bar as separate elements of a String[] to Runtime.exec, and additionally restrict bar to a benign subset of characters (for example, alphanumerics and a few safe punctuation characters). If validation fails, we can either reject the request or replace unsafe characters. Concretely:

• Keep retrieval of param and bar as is (or you may also choose to validate earlier).
• Introduce a simple validation/normalization step before executing the command, e.g., by stripping characters that could alter shell syntax.
• Change r.exec(cmd + bar); to use the overload r.exec(String[] cmdarray), building cmdarray from the OS command (which getOSCommandString("echo") likely returns as a base command, e.g., "cmd.exe /c echo ") and the (validated) bar as a separate argument. Since we cannot modify Utils.getOSCommandString, and we don’t know whether it returns a single token or multiple tokens separated by spaces, the safest minimally invasive approach in this snippet is to avoid concatenating user input at all and instead neutralize it before concatenation. Given the constraints and that we must not change imports beyond standard ones, we can implement a basic sanitizer method in this class that strips characters commonly used for command injection (&, |, ;, `, <, >, newline, carriage return).

Therefore, in this file:

• Add a private static helper method sanitizeForCommand(String input) that removes disallowed characters from input.
• Before executing the command, compute String safeBar = sanitizeForCommand(bar);.
• Replace r.exec(cmd + bar); with r.exec(cmd + safeBar);.

This keeps overall behavior (echoing back the header value) but avoids directly passing potentially dangerous metacharacters to the shell.

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In general, the safest way to fix uncontrolled command line usage is to avoid building a single command string with concatenation and instead call Runtime.exec(String[] cmdarray) (or ProcessBuilder) so that user input is passed as a distinct argument. This prevents the input from altering the structure of the command itself and removes the need for fragile regex‑based sanitization. Additionally, avoid executing any command at all when it is not strictly necessary or when input does not meet explicit validation rules.

For this concrete code, the best minimal fix while preserving behavior is:

• Stop appending safeBar directly to the command string.
• Remove the custom sanitizeForCommand method since we will not interpolate into a shell command line.
• Build an argument array where the first element is the OS command obtained from Utils.getOSCommandString("echo") and the second element is the (decoded) header value bar.
• Use Runtime.exec(String[] cmdarray) with that array.

Because getOSCommandString("echo") likely returns a full command string (possibly including spaces), we need to split it into the executable and its fixed arguments before appending the user-controlled bar. We can do this using String.split(" ") on the command string, then construct a new array with one extra slot for bar. This keeps the user input as a separate argument and maintains existing functional behavior (echoing the user-provided value). All changes are confined to Benchmark00302.java: remove the sanitizer method and adjust the execution logic inside doPost.