Failed to unprotect memory

[houxinlin]

#include <funchook.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

static int  (*getpid_func)();

static int getpid_hook() {
    printf("origin getpid==%d\n",getpid_func());
    return 0;
}

int main() {
    funchook_t *funchook = funchook_create();

    getpid_func = getpid;
    funchook_prepare(funchook, (void**)&getpid_func, getpid_hook);

    if (funchook_install(funchook, 0) != FUNCHOOK_ERROR_SUCCESS) {
        printf("%s\n", funchook_error_message(funchook));
    }

    printf("%d\n",getpid());
    return 0;
}

output

Failed to unprotect memory 0xffff876d7000 (size=4096, prot=read,write,exec) <- 0xffff876d76b0 (size=8, error=Invalid argument)
3358211

[kubo]

@houxinlin
Thanks for the report with sample code. Could you post environment information also?
Your code works fine on my Linux box (Ubuntu 22.04 x86_64 on physical machine).

[houxinlin]

@houxinlin Thanks for the report with sample code. Could you post environment information also? Your code works fine on my Linux box (Ubuntu 22.04 x86_64 on physical machine).

Thank you for getting back to me. I noticed there hasn't been much activity on your GitHub lately, so I thought you might not be maintaining this repository anymore. I'm running on an arm64 architecture with CentOS as the operating system, and I encountered this error. It works fine on x86 systems, though.

[kubo]

Could you check the page size by running the following command?

$ getconf PAGE_SIZE
4096

If the output isn't 4096, could you replace PAGE_SIZE at this line with the value?

The page size of ARM64 CPU seems 4KB or 64KB according to https://www.kernel.org/doc/html/next/arch/arm64/memory.html.
It is all 4KB in my ARM64 machines. It may not be 4KB in yours.

[houxinlin]

Could you check the page size by running the following command?

$ getconf PAGE_SIZE
4096

If the output isn't 4096, could you replace PAGE_SIZE at this line with the value?

The page size of ARM64 CPU seems 4KB or 64KB according to https://www.kernel.org/doc/html/next/arch/arm64/memory.html. It is all 4KB in my ARM64 machines. It may not be 4KB in yours.

After my modifications, it started functioning properly, but issues persist when the system has different PAGE_SIZE values. I attempted replacing all instances of 'page_size' with 'sysconf(_SC_PAGE_SIZE)' to dynamically fetch the size during runtime. After testing, it ran without errors, but could this approach lead to any other unexpected behaviors?

[kubo]

but could this approach lead to any other unexpected behaviors?

No. It is okay.