Which of the following attacks can stack canaries defeat? Writing a stack-allocated buffer at an attacker-chosen offset, perhaps one outside the buffer's bounds O Overflowing (e.g., via a call to strcpy) a stack-allocated buffer, overwriting the return address Reading from a stack-allocated buffer at an attacker-chosen offset outside the buffer's bounds Overflowing (e.g., via a call to strcpy) a heap-allocated struct field into an adjacent field in the same struct which contains a function pointer

Which of the following attacks can stack canaries defeat? Writing a stack-allocated buffer at an attacker-chosen offset, perhaps one outside the buffer's bounds O Overflowing (e.g., via a call to strcpy) a stack-allocated buffer, overwriting the return address Reading from a stack-allocated buffer at an attacker-chosen offset outside the buffer's bounds Overflowing (e.g., via a call to strcpy) a heap-allocated struct field into an adjacent field in the same struct which contains a function pointer

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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3. In the StackGuard approach to solving the buffer overflow problem, the compiler inserts a canary value on the memory location before the retum address in the stack. The canary value is randomly generated. When there is a return from the function call, the compiler checks if the canary value has been overwritten or not. Do you think this approach would work? Why or why not?
1. Show the contents of the stack as you trace the algorithm, checkBalance, for the following expression: (a (b* c) / [d+e] / f )-g} 2. Show the contents of the two stacks as you trace the algorithm, evaluateInfix, to evaluate the following infix expression. Assume that a = 2, b = 3, c = 4, d = 5 (a + b) / (c-d) -5
3. Which stack protection techniques are vulnerable to return-orlented programming? a. Stack Canaries b. Address space layout randomization c. Limiting Executable Code Regions 4. In malloclab, several students implemented an optimization where small blocks would be allocated at the beglinning of a free block, and large blocks would be allocated at the end of a free block. In what way was this useful on some traces? a. It increases the memory utilization due to less Internal fragmentation. b. It increagos tho momory utlization duo to moro coaloscing opportunities. c. Itincreases the throughput due to smaller free lists. d. It increases the throughput due to better temporal locality in caches. 5. After a forki), to access which datastnuctures, should the resulting two processes synchronize? а. Неар b. Stack c. Registers d. Globals e. Program Code
UNJOWN Browser + Webcam Time Left:1:25:10 Wondemu Damite: Attempt 1 Exit Switch Statement; Case 1: If (S.isEmpty != true) {Y = S.top () Printout ("Stack Element: " + Y): S.pop (); Else Printout "Sorry, stack is empty": Exit Switch Statement; Case 2: Q. enqueue (X): Exit Switch Statement; If (Q.isEmpty != true) {Y = Q.front(); Printout! Q.dequeue () ; Case 3: ("Queue Element: + Y); Else Printout "Sorry, queue is empty"; Exit Switch Statement; } //end of Switch statement Read next input value to X; } //end of While statement Printout ("Stack Elements are: "); While ((S.isEmpty != true) Y = S.top) Printout on newline (Y); S.pop(): Printout ("Queue Elements are: "); While ((Q.isEmpty != true) Y = Q.front() Printout on newline (Y); %3! Q.dequeue () :
Complete the following code. The goal is to implement the producer-consumer problem. You are expected to extend the provided C code to synchronize the thread operations consumer() and producer() such that an underflow and overflow of the queue is prevented. You are not allowed to change the code for implementing the queue operations, that is the code between lines 25 and 126 as shown in the screenshot. You must complete the missing parts as shown in the screenshot as well as complete the missing codes of producer and consumer. #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <time.h> #include <pthread.h> #include <semaphore.h> #include <errno.h> #include <fcntl.h> #define MAX_LENGTH_CAP 100 #define INIT -127 #define UNDERFLOW (0x80 + 0x02) #define OVERFLOW 0x80 + 0x01 #define BADPTR (0x80 + 0x03) #define CONSUMER_TERMINATION_PROBABILITY 40 #define PRODUCER_TERMINATION_PROBABILITY 30 // ============= LOCKED…
Select the statements that apply to the use of the frame pointer. EBP is often called the base pointer or frame pointer because it holds the base address of the stack frame. EBP does not changes value during the procedure. EBP need not be restored to its original value when a procedure returns. A procedure can explicitly access stack parameters using constant offsets from EBP.
Complete the following code. The goal is to implement the producer-consumer problem. You are expected to extend the provided C code to synchronize the thread operations consumer() and producer() such that an underflow and overflow of the queue is prevented. You are not allowed to change the code for implementing the queue operations, that is the code between lines 25 and 126 as shown in the Figure below. You must complete the missing parts between lines 226-261 as shown in the screenshot.
Write an Arm Assembly Program that does the following:•Stores on the stack a list of words of memory where the first element of the list is how manyremaining elements are in the list, and the rest of the elements in the list are initialized tosome random values.– Example:list: 6, -3, 4, 5, 9, 22, 99//stores a list of the 6 elements -3, 4, 5, 9, 22, 99•At the end of the program, register r0 should hold the sum of only the negative values in thearray (nonnegative elements are ignored).•Note that your program must work correctly even if the values stored in the list are changed.
PP 13.3 The LinkedStack class should be updated to utilise a fake record at the top of the list. PP 13.4 Make a straightforward graphical programme that enables push, pop, and peek operations on stacks and displays the resulting stack in a text area using the toString function. PP 13.3 The LinkedStack class should be updated to utilise a fake record at the top of the list. PP 13.4 Make a straightforward graphical programme that enables push, pop, and peek operations on stacks and displays the resulting stack in a text area using the toString function.
- What is the address of an integer that was first pushed on to stack?- What is the value in Hex and signed decimal of an integer that was first pushed on to stack?- What is the offset from FRAME POINTER to an integer that was first pushed on to stack?- What is the address of an integer that was Last pushed on to stack?- What is the value in Hex and signed decimal of an integer that was Last pushed on to stack?- What is the offset from FRAME POINTER to an integer that was Last pushed on to stack?- Based on the data shown Figure 2.,Can you determine if Frame pointer points to an address or a value? Please circle around your answer. Please explain.
What are the contents of the stack num after the following statements execute? Assume that NumStack is a class that implements the interface StackInterface. StackInterface num = new NumStack<>(); num.push(111); num.push(num.pop()); num.push(222); num.push(333); num.push(444); num.push(num.pop()); int n = num.pop(); num.push(num.peek()); q2. Show the contents of the stack as you trace the algorithm checkBalance, given in Segment 5.8, for each of the following expressions: a. a {b [c * (d + e)] - f } b. {a (b * c) / [d + e] / f )- g} c. a {b [c - d] e ]) f q3. Imagine a linked implementation of the ADT stack that places the top entry of the stack at the end of a chain of linked nodes. Describe how you can define the stack operations push, pop, and peek so that they do not traverse the chain.
A counter automaton is a pushdown automaton that only uses one stack symbol (in additionto the bottom of the stack marker). This means that the stack acts as a simple counter: the push operationincreases the counter, the pop operation decreases it, and you can check if the counter is currently set to 0by looking for the bottom of the stack. In particular, you can not store a string over an arbitrary alphabeton the stack. For example, the automaton for anbn we have seen in class is a counter automaton.Let L = {w ∈{a, b}∗|w contains the same number of symbols a and b}.(2.a) Build a counter automaton accepting the language L. As in Question 1, describe the algorithmused by your automaton, and draw a transition diagram.(2.b) Write down an accepting computation of your automaton on the string abbbabaa.