CS271 Week 7

Suppose that you are given the following program (with memory addresses shown on the left). What hexadecimal value does EIP hold immediately after "inc EAX" has executed? .data 0x100 x DWORD 153461 0x104 y BYTE 37 0x105 z BYTE 90 .code main PROC 0x12 push x 0x17 mov AH, y 0x1C mov AL, z 0x21 call someProcedure 0x26 inc EAX 0x2B mov EBX, z 0x30 xor EAX, EBX 0x35 exit main ENDP END MAIN

2bh

The RET instruction (without operands) will pop how many bytes off the stack?

4

Given the following partial data segment, what value would I put in the brackets in list99 to access the 12th element of list? (Ignore the .0000 that Canvas may append to your answer). .MAX = 50 .data list DWORD MAX DUP(0) a DWORD 25 b DWORD 15

44

Given list, an array of WORDs, what element is addressed by list[8]? Hint: It's Love.

5th Element

Suppose that you are given the following program. Inside someProcedure, what numerical operand should be used with the RET instruction? .data x DWORD 153461 y BYTE 37 z BYTE 90 .code main PROC push x push y push z call someProcedure inc EAX mov EBX, z xor EAX, EBX exit main ENDP END MAIN

6

Given the following register states, and using Base Indexed Addressing, which of the following lines of code will move the 11th element of the list array (of DWORDs) to the EAX register? EDX register contans the address of the first element of list. ESI register contains the address of the eleventh element of list. EBX register contains the value 40,

mov eax, [edx + ebx]

Given the following register states, and using Indexed Addressing, which of the following lines of code will move the 11th element of the list array (of DWORDs) to the EAX register? EDX register contans the address of the first element of list. ESI register contains the address of the eleventh element of list. EBX register contains the value 40,

mov eax, list[ebx]

The following two instructions are equivalent. ret ret 4

ret ret 4

If you reference a point beyond the end of an array in MASM (for example, the address of the what would be the 105th element of a 100-element array), what happens?

You attempt to access whatever data bytes are stored there.

For this problem, suppose that you are working with the partial data segment given below. Assume that the memory address of balance is 0x44. What hexadecimal address belongs to the first item in history? HISTLIMIT = 100 .data balance DWORD 0 account WORD ? history WORD HISTLIMIT DUP(?) isValid BYTE 0

0x4A

The following instruction will increment the stack pointer (ESP) by how many bytes? (Ignore the .0 after the number. Canvas insists on pushing decimals even when kindly asked not to). ret 16

20

Register Indirect addressing is defined as follows:

Accessing memory through an address stored in a register.

The stack frame inside a procedure is also known as the ____________.

Activation Record