3. Which stack protection techniques are vulnerable to return-orlented programming?a. Stack Canariesb. Address space layout randomizationc. Limiting Executable Code Regions4. In malloclab, several students implemented an optimization where small blocks would beallocated at the beglinning of a free block, and large blocks would be allocated at the endof 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 processessynchronize?а. Неарb. Stackc. Registersd. Globalse. Program Code

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3. Which stack protection techniques are vulnerable to retun-oriented programming? a. Stack Canaries b. Address space layout randomization c. Limiting Executable Code Regions

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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2.     For the code below, draw a picture of the program stack when the function partition() is called the 2nd time. # extracted from suquant's reply at # https://stackoverflow.com/questions/18262306/quicksort-with-python def partition(array, begin, end):     pivot = begin     for i in range(begin+1, end+1):         if array[i] <= array[begin]:             pivot += 1             array[i], array[pivot] = array[pivot], array[i]     array[pivot], array[begin] = array[begin], array[pivot]     return pivot def quicksort(array, begin, end):     if begin >= end:         return     pivot = partition(array, begin, end)     quicksort(array, begin, pivot-1)     quicksort(array, pivot+1, end) # added calling code if __name__ == "__main__":     mylist = [8, 2, 17, 4, 12]     quicksort(mylist, 0, 4)
Someone tries to fix the stack based buffer overflow problem as follows, is it secure now? why?why not? Are there any other issues within the function's implementation below? Please explain your reasoning. int bof(char *str, int size) {   char *buffer = (char *) malloc(size);   strcpy(buffer, str);   return 1; }
Someone tries to fix the stack based buffer overflow problem as follows, is it secure now? why? Are there any other issues within the function's implementation below? Explain your reasoning. int bof(char *str, int size) {   char *buffer = (char *) malloc(size);   strcpy(buffer, str);   return 1; }
In C, using this interface: void setSortThreads(int count);void sortThreaded(char** array, unsigned int count); How can you modify the following quicksort program in order to use multithreading, with the goal of performing faster than qsort for large data sets? Use basic parallelization and limit the number of threads to the amount held by the global variable maximumThreads, specified by the user (when they call setSortThreads in the main function). If possible it would be helpful to test the code on a big text file, like maybe the dictionary. I'll include a sample main function at the end that I have been using. You would need your own text file to test it on, though. #include <stdlib.h>#include <string.h>#include <pthread.h>#define SORT_THRESHOLD 40typedef struct _sortParams {char** array;int left;int right;} SortParams;static int maximumThreads; /* maximum # of threads to be used *//* This is an implementation of insert sort, which although it is *//*…
In C, using this interface: void setSortThreads(int count);void sortThreaded(char** array, unsigned int count); How can you modify the following quicksort program in order to use multithreading, with the goal of performing faster than qsort for large data sets? Use basic parallelization and limit the number of threads to the amount held by the global variable maximumThreads, specified by the user (when they call setSortThreads in the main function). If possible it would be helpful to test the code on a big text file, like maybe the dictionary. I'll include a sample main function at the end that I have been using. You would need your own text file to test it on. #include <stdlib.h> #include <stdio.h>#include <string.h>#include <pthread.h> #include <time.h>#define SORT_THRESHOLD 40typedef struct _sortParams {char** array;int left;int right;} SortParams;static int maximumThreads; /* maximum # of threads to be used *//* This is an implementation of…
A common implementation of sequential files on disk has each block point to its successor, which may be any block on the disk. This method requires a constant amount of time to write a block (as the file is originally written), to read the first block in the file, and to read the ith block, once you have read the 1 - 1” block. Reading the lth block therefore requires time proportional to 1. Show how by adding just one additional pointer per node, you can keep all the other properties, but allow the lth block to be read in time proportional to log I. [Hint: heaps have implicit pointers from node I to what other nodes?] Explain what the algorithm for reading the th block has in common with an algorithm for raising a number to the ith power in time proportional to log 1.
Someone tries to fix the stack based buffer overflow problem as follows, is it secure now? why? Are there any other issues within the function's implementation below? int bof(char *str, int size) { char *buffer = (char *) malloc(size); strcpy(buffer, str); return 1; }
6.Need ri Write a JAVA program that will maintain a phone directory using a Linked-List. The program should be able to perform the following operations: Add persons details (first name, last name, phone number, city, address, sex and email) to the phone directory, where phone numbers in the directory have to be unique. (Note: each person record will store in one node in the linked-list and insert each person to the last) Delete any person details by a given phone number. Update telephone number by providing person first name. Display all details of persons from a phone directory. Search telephone number based on person first name. (Note: use sequential search to find all telephones for the given first name) Sort all persons in the phone directory ascending based on person first name. (Note: use bubble or selection sort to arrange the entire phone directory.
For this assignment you need to write a parallel program in C++ using OpenMP for vector addition. Assume A, B, C are three vectors of equal length. The program will add the corresponding elements of vectors A and B and will store the sum in the corresponding elements in vector C (in other words C[i] = A[i] + B[i]). Every thread should execute approximately equal number of loop iterations. The only OpenMP directive you are allowed to use is: #pragma omp parallel num_threads(no of threads) The program should take n and the number of threads to use as command line arguments: ./parallel_vector_addition Where n is the length of the vectors and threads is the number of threads to be created. Pseudocode for Assignment mystart = myid*n/p; // starting index for the individual thread myend = mystart+n/p; // ending index for the individual thread for (i = mystart; i < myend; i++) // each thread computes local sum do vector addition // and later all local sums combined. As an input vector A,…
During the sockets lab we cast the second parameter from a struct sockaddr_in to a struct sockaddr. struct sockaddr_in address; /* ... */ bind(server_fd, (struct sockaddr*)&address, sizeof(address)) This provides a limited form of polymorphism: bind only needs the first few fields of its struct, and both struct sockaddr_in and struct sockaddr have the same fields at those addresses. Consider the following example: typedef struct { float x; float y; float z; } point3D; typedef struct { float x; float y; } point2D; float distance(point2D *a1, point2D *a2) { /* ... */ } int main() { point2D a = { .x = 2.1, .y = 3.0 }; point3D b = { .x = 4.1, .y = 4.3, .z = 4.0 }; // Call distance function with a and b } How would you pass a and b to the distance function? If several work, pick one that will not create warnings. A. distance(a, b); B. distance(a, (point2D)b); C. distance(&a, &b); D. distance(&a, &(point2D)b); E. distance(&a, (point2D*)&b); F. none of…
1. For the code below, draw a picture of the program stack when the function partition() is called the first time. You only have to draw the part of the stack for quicksort() and partition(). # extracted from suquant's reply at # https://stackoverflow.com/questions/18262306/quicksort-with-python def partition(array, begin, end): pivot = begin for i in range(begin+1, end+1): if array[i] <= array[begin]: pivot += 1 array[i], array[pivot] = array[pivot], array[i] array[pivot], array[begin] = array[begin], array[pivot] return pivot def quicksort(array, begin, end): if begin >= end: return pivot = partition(array, begin, end) quicksort(array, begin, pivot-1) quicksort(array, pivot+1, end) # added calling code if __name__ == "__main__": mylist = [8, 2, 17, 4, 12] quicksort(mylist, 0, 4)
do for heaps.I. Create a performance driver client programme that inserts to fill a priority queue, then removes the maximum to remove half the keys, then inserts to fill it up again, then removes the maximum to remove all the keys, repeating this process on random sequences of keys ranging in length from small to large; measures the time taken for each run; and prints out or plots the average running times.