What is the meaning of argument type: "const char user const user argv"

Question

I see this kind of type in the execve syscall:

asmlinkage long sys_execve(const char __user *filename,
const char __user *const __user *argv,
const char __user *const __user *envp);


do_execve(struct filename *filename,
const char __user *const __user *__argv,
const char __user *const __user *__envp)

What is the meaning of

const char __user *const __user *

?

Possible duplicate of [What are the implications of the linux \_\_user macro?](https://stackoverflow.com/questions/4521551/what-are-the-implications-of-the-linux-user-macro) — StoryTeller - Unslander Monica, Jul 30 '17 at 22:50

score 3 · Answer 1 · edited Jul 17 '18 at 06:17

3

As you read through the list of file_operations methods, you will note that a number of parameters include the string __user. This annotation is a form of documentation, noting that a pointer is a user-space address that cannot be directly dereferenced. For normal compilation, __user has no effect, but it can be used by external checking software to find misuse of user-space addresses.

edited Jul 17 '18 at 06:17

Alien

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answered Jul 17 '18 at 05:10

manish

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Add link to adequate documentation for reference – Shubham Jul 17 '18 at 05:35

What is the meaning of argument type: "const char __user *const __user *argv"

1 Answers1

What is the meaning of argument type: "const char user const user argv"