STRCPY seg fault

[dissectcode2]

I know this is a common forum post but I don't see how they fit with my code/problem:

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

void cds( char *cdsprefix )
{

    // default
    char *prefix = "somereally_long_string_09";

    if( cdsprefix )
    {

	printf("we passed in a prefix...\n\n");

	printf("strlen of prefix : %d\n", strlen(prefix)); //25
	printf("strlen of input : %d\n", strlen(cdsprefix)); //3
	

	strcpy( prefix, cdsprefix ); //SEG FAULT HERE!!!!!!!!!!

	printf("i guess that strcpy passed...\n\n");
    }

    printf("now prefix string is : %s\n\n\n", prefix);    

}



int main(void)
{
	
	char *abc = "abc";
	char *rest = NULL;
	rest = (char *)(malloc(strlen(abc) * sizeof(char) + 1 ));

	strcpy( rest, abc );

	printf("rest is now : %s \n\n\n", rest);


	/////////////other test ///////////////

	// we pass in rest
	cds(rest);


	return 7;
}

please help, i have performed many experiements and can't pin point the issue. thank you

[dissectcode2]

I FOUND THE ANSWER!!!

http://stackoverflow.com/questions/1405594/writing-into-c-string

relief!!