CODEWITHSUNDEEP
clinuxwebservercgihosting
rn42v
rn42v

Reputation: 97

"hello world" c cgi script crashes on server”

I'm trying to execute a simple c cgi-script on a hosted webserver. I compiled this code:

#include <stdio.h>

int main(){
    printf("Content-type: text/plain\n\n");
    printf("<html>\n");
    printf("<head><title>Testing CGI-Scripts</title></head>\n");
    printf("<body>\n");
    printf("<h1>Hello World</h1>\n");
    printf("</body>\n");
    printf("</html>\n");
    return 0; 
}

with gcc -o index.cgi index.c, uploaded the binary to the cgi-bin directory and changed the permission to 755. Yet when executing the script (url/cgi-bin/index.cgi) it causes a core-dump and I'm getting "500 Internal Server Error". Analyzing the core-dump with gdb got me "Cannot access memory at address 0x3000000000008" and the same line with "0x3000000000000".

I tried:

(Analysis with gdb from the static binary: 

Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000401e82 in __libc_start_main ()

)

My System: Arch Linux, kernel 4.20.12 x86_64

Server: CloudLinux 7, kernel 3.10.0-962.3.2.lve1.5.24.8.el7 x86_64

I do not have shell access, unfortunately.

Edit: Solution:

Building a static binary on a virtual machine with CentOS (on which the Servers distro is based on) installed worked!

Upvotes: 2

Views: 191

Answers (1)

torstenvl
torstenvl

Reputation: 785

The libraries and linker behavior may vary widely. The two distributions in question aren't even running on the same major kernel version. It sounds like you're compiling against a significantly newer version of glibc than the one that exists on your server.

I recommend you set up cross-compilation or run CloudLinux 7 in a virtual machine and compile in the VM.

Upvotes: 1

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