KernelAddressSanitizer

The KernelAddressSanitizer (KASan) detects dynamic memory errors in the Linux kernel.^[10] Kernel instrumentation requires a special feature in the compiler supplying the -fsanitize=kernel-address command line option, since kernels do not use the same address space as normal programs.^[11][12]

ASan: Heap-use-after-free

// To compile: g++ -O -g -fsanitize=address heap-use-after-free.cc
int main(int argc, char **argv) {
  int *array = new int[100];
  delete [] array;
  return array[argc];  // BOOM
}

$ ./a.out
==5587==ERROR: AddressSanitizer: heap-use-after-free on address 0x61400000fe44 at pc 0x47b55f bp 0x7ffc36b28200 sp 0x7ffc36b281f8
READ of size 4 at 0x61400000fe44 thread T0
    #0 0x47b55e in main /home/test/example_UseAfterFree.cc:5
    #1 0x7f15cfe71b14 in __libc_start_main (/lib64/libc.so.6+0x21b14)
    #2 0x47b44c in _start (/root/a.out+0x47b44c)

0x61400000fe44 is located 4 bytes inside of 400-byte region [0x61400000fe40,0x61400000ffd0)
freed by thread T0 here:
    #0 0x465da9 in operator delete[](void*) (/root/a.out+0x465da9)
    #1 0x47b529 in main /home/test/example_UseAfterFree.cc:4

previously allocated by thread T0 here:
    #0 0x465aa9 in operator new[](unsigned long) (/root/a.out+0x465aa9)
    #1 0x47b51e in main /home/test/example_UseAfterFree.cc:3

SUMMARY: AddressSanitizer: heap-use-after-free /home/test/example_UseAfterFree.cc:5 main
Shadow bytes around the buggy address:
  [...]
  0x0c287fff9fb0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c287fff9fc0: fa fa fa fa fa fa fa fa[fd]fd fd fd fd fd fd fd
  0x0c287fff9fd0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  [...]
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:     fa
  Heap right redzone:    fb
  Freed heap region:     fd
  Stack left redzone:    f1
  Stack mid redzone:     f2
  Stack right redzone:   f3
  Stack partial redzone: f4
  Stack after return:    f5
  Stack use after scope: f8
  Global redzone:        f9
  Global init order:     f6
  Poisoned by user:      f7
  ASan internal:         fe
==5587==ABORTING

ASan: Heap-buffer-overflow

// RUN: clang++ -O -g -fsanitize=address heap-buf-of.cc && ./a.out
int main(int argc, char **argv) {
  int *array = new int[100];
  array[0] = 0;
  int res = array[argc + 100];  // BOOM
  delete [] array;
  return res;
}

==25372==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x61400000ffd4 at pc 0x0000004ddb59 bp 0x7fffea6005a0 sp 0x7fffea600598
READ of size 4 at 0x61400000ffd4 thread T0
    #0 0x46bfee in main /tmp/main.cpp:4:13

0x61400000ffd4 is located 4 bytes to the right of 400-byte region [0x61400000fe40,0x61400000ffd0)
allocated by thread T0 here:
    #0 0x4536e1 in operator delete[](void*)
    #1 0x46bfb9 in main /tmp/main.cpp:2:16

ASan: Stack-buffer-overflow

// RUN: clang -O -g -fsanitize=address stack-buf-of.cc && ./a.out
int main(int argc, char **argv) {
  int stack_array[100];
  stack_array[1] = 0;
  return stack_array[argc + 100];  // BOOM
}

==7405==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fff64740634 at pc 0x46c103 bp 0x7fff64740470 sp 0x7fff64740468
READ of size 4 at 0x7fff64740634 thread T0
    #0 0x46c102 in main /tmp/example_StackOutOfBounds.cc:5

Address 0x7fff64740634 is located in stack of thread T0 at offset 436 in frame
    #0 0x46bfaf in main /tmp/example_StackOutOfBounds.cc:2

  This frame has 1 object(s):
    [32, 432) 'stack_array' <== Memory access at offset 436 overflows this variable

ASan: Global-buffer-overflow

// RUN: clang -O -g -fsanitize=address global-buf-of.cc && ./a.out
int global_array[100] = {-1};
int main(int argc, char **argv) {
  return global_array[argc + 100];  // BOOM
}

==7455==ERROR: AddressSanitizer: global-buffer-overflow on address 0x000000689b54 at pc 0x46bfd8 bp 0x7fff515e5ba0 sp 0x7fff515e5b98
READ of size 4 at 0x000000689b54 thread T0
    #0 0x46bfd7 in main /tmp/example_GlobalOutOfBounds.cc:4

0x000000689b54 is located 4 bytes to the right of 
  global variable 'global_array' from 'example_GlobalOutOfBounds.cc' (0x6899c0) of size 400

UBSan: nullptr-dereference

// RUN: g++ -O -g -fsanitize=null null-dereference.c && ./a.out
int main(int argc, char **argv) {
  const char * ptr = nullptr;
  return *ptr;  // BOOM
}

null-dereference.c:4:10: runtime error: load of null pointer of type 'const char'
Segmentation fault (core dumped)