I looking in ida on arm linux binary . I can see there that there is ioctl call


fd is fd to /dev/module. ,req is some 4bytes and num is some number.

How can I understand what this ioctl call do?

What req number mean?

Where can I find the handle of this ioctl?

  • You should study a bit that syscall, in general ioctl is for access drivers, and is very dependent of the driver, in your case /dev/module, do a man ioctl and you will understand better how works, there is plenty of information about it, just google it
    – camp0
    Commented Jun 14, 2019 at 20:04

1 Answer 1


You need to find the driver (either a separate binary or built-in into the kernel) which publishes this dev file entry, the code to handle the ioctl request will be in it.

Here’s an article with an example of ioctl handler:


String search for the file name may be the quickest way to do find the required binary/code area.

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