Java runtime.exec() Error tainted command[1] = null

Question

I got this error when executing a command in Android shell via runtime.getRuntime.exec(command,arguments,working directory)b

FATAL EXCEPTION: main
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               Process: com.learning, PID: 23705
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               java.lang.NullPointerException: taintedCommand[1] == null
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at java.lang.ProcessManager.exec(ProcessManager.java:184)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at java.lang.Runtime.exec(Runtime.java:174)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at com.learning.BackgroundJob.<init>(BackgroundJob.java:38)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at com.learning.MainActivityTerminal$100000000.onEditorAction(MainActivityTerminal.java:58)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at android.widget.TextView.onEditorAction(TextView.java:4489)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at com.android.internal.widget.EditableInputConnection.performEditorAction(EditableInputConnection.java:143)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at com.android.internal.view.IInputConnectionWrapper.executeMessage(IInputConnectionWrapper.java:304)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at com.android.internal.view.IInputConnectionWrapper$MyHandler.handleMessage(IInputConnectionWrapper.java:78)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at android.os.Handler.dispatchMessage(Handler.java:102)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at android.os.Looper.loop(Looper.java:135)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at android.app.ActivityThread.main(ActivityThread.java:5318)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at java.lang.reflect.Method.invoke(Native Method)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at java.lang.reflect.Method.invoke(Method.java:372)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:922)
04-07 02:56:18.539 23705 23705 E   AndroidRuntime                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:717)
04-07 02:54:04.839 23439 23439 W   System.err                                   at java.lang.reflect.Method.invoke(Method.java:372)
04-07 02:54:04.839 23439 23439 W   System.err                                   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:922)
04-07 02:54:04.839 23439 23439 W   System.err                                   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:717)
04-07 02:54:04.839 23439 23439 W   System.err                                   Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
04-07 02:54:04.839 23439 23439 W   System.err                                   at libcore.io.Posix.open(Native Method)
04-07 02:54:04.839 23439 23439 W   System.err                                   at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
04-07 02:54:04.839 23439 23439 W   System.err                                   at libcore.io.IoBridge.open(IoBridge.java:442)
04-07 02:54:04.839 23439 23439 W   System.err                                   ... 18 more

code

Process process;
        try {
            process = Runtime.getRuntime().exec(progArray, env, new File(cwd));
        } catch (IOException e) {
            mProcess = null;
            // TODO: Visible error message?
            Log.e(LOG_TAG, "Failed running background job: " + processDescription, e);
            return;
        }

variables progarry command to execute, env current environment, cwd current working directory.

Answer 1

Runtime.exec() throws a NullPointerException if cmdarray is null, or one of the elements of cmdarray is null, or one of the elements of envp is null.

So, the best you can do is to check for these conditions, for example

if (progArray == null) {
    // do something else or log
    return;
} 
...