These are the instructions to root Samsung Galaxy S5 SM-G900S smartphones running on the Android 6.0.1 Marshmallow software updates by flashing an updated version of the CF-Auto-Root tool that gives your smartphone a working version of SuperSU.

REQUIREMENTS

• The following guide is made for the Samsung Galaxy S5 smartphone with the SM-G900S model number and no other. Do not flash the CF-Auto-Root package you find in this guide on any other model number of the Samsung Galaxy S5 smartphone, or else you risk bricking that device.
• You must have a computer that is running a version of Windows to use this guide. The flashing tool we are using to flash the CF-Auto-Root package is not going to work on any other operating systems.

BEFORE WE BEGIN

• Unlock the Developer Options menu on the Samsung Galaxy S5 smartphone by tapping on the Settings icon > About Device and then tap where it shows you the Build Number on the screen. Keep tapping that build number until it tells you that you are now using the device as a developer.
• Since you are now using the Samsung Galaxy S5 as a developer according to the Android OS, you are now able to turn on the USB Debugging Mode from within the Developer Options menu. Do that now so you can use the guide by tapping on the Settings icon > Developer Options and then tap where it shows an empty box next to the words USB Debugging. You can leave the Developer Options menu after checking the USB Debugging Mode box, and the Android operating system will remember your preferences.
• Download and install the Samsung USB Drivers on the computer before you start with the guide so the apps can detect your smartphone on the computer such as the flashing tool we are about to use.

HOW TO ROOT SAMSUNG GALAXY S5 SM-G900S ON ANDROID 6.0.1 MARSHMALLOW

1. Download the updated version of the CF-Auto-Root tool that works for the S5 G900S on Android 6.0.1 Marshmallow from here.
2. Extract the rooting package to the desktop of the computer.
3. Double-click on the Odin executable file so that your flashing tool opens up on the desktop.
4. Make sure that you have installed the Samsung USB Drivers before proceeding to the next step.
5. Connect the Samsung Galaxy S5 smartphone to the computer in download mode.
6. Check for a blue or yellow ID: COM port color coming from the Odin user interface which is letting you know that your device is connected a.k.a the drivers you installed are working correctly.
7. Click the AP button and browse the desktop of the computer for the rooting file that you extracted earlier.
8. Leave all default settings from the Odin user interface.
9. Click the Start button from the Odin user interface.
10. Wait until you see a pass message inside a green box from the Odin user interface before unplugging the smartphone from the computer.

In conclusion, that is how to root Samsung Galaxy S5 SM-G900S running on the Android 6.0.1 Marshmallow software update. You will find the S5 smartphone automatically reboots now, and you can find the SuperSU app available from the app drawer.