Sanitizers support for ARC ========================== Sanitizers functionality has been enabled for ARC. Please notice that support for the sanitizers is limited for Linux, when running with upcoming glibc (GNU C Library) port. ARC supports the following sanitizers: * Address, * Memory, * Undefined behavior and * Leak sanitizers. AddressSanitizer is a fast memory error detector. It consists of a compiler instrumentation module and a run-time library. The tool can detect the following types of bugs: * Out-of-bounds accesses to heap, stack and globals * Use-after-free * Use-after-return (runtime flag ASAN_OPTIONS=detect_stack_use_after_return=1) * Use-after-scope (clang flag -fsanitize-address-use-after-scope) * Double-free, invalid free * Memory leaks (experimental) Typical slowdown introduced by AddressSanitizer is 2x. MemorySanitizer is a detector of uninitialized reads. It consists of a compiler instrumentation module and a run-time library. Typical slowdown introduced by MemorySanitizer is 3x. UndefinedBehaviorSanitizer (UBSan) is a fast undefined behavior detector. UBSan modifies the program at compile-time to catch various kinds of undefined behavior during program execution, for example: * Using misaligned or null pointer * Signed integer overflow * Conversion to, from, or between floating-point types which would overflow the destination * See the full list of available checks below. UBSan has an optional run-time library which provides better error reporting. The checks have small runtime cost and no impact on address space layout or ABI. LeakSanitizer is a run-time memory leak detector. It can be combined with AddressSanitizer to get both memory error and leak detection, or used in a stand-alone mode. LSan adds almost no performance overhead until the very end of the process, at which point there is an extra leak detection phase. We included in this document a few example as reference to the use of the sanitizers. For a clearer view of how to use the sanitizers, or further examples, please refer to `Clang documentation`_ Address Sanitizer Examples -------------------------- Heap-use-after-free ^^^^^^^^^^^^^^^^^^^ .. code-block:: c // To compile: clang++ -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 } .. code-block:: text $ ./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:7 #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:6 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:5 SUMMARY: AddressSanitizer: heap-use-after-free /home/test/example_UseAfterFree.cc:7 main Shadow bytes around the buggy address: 0x0c287fff9f70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c287fff9f80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c287fff9f90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c287fff9fa0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 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 0x0c287fff9fe0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x0c287fff9ff0: fd fd fd fd fd fd fd fd fd fd fa fa fa fa fa fa 0x0c287fffa000: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c287fffa010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 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 Heap-buffer-overflow ^^^^^^^^^^^^^^^^^^^^ .. code-block:: c // RUN: clang++ -O -g -fsanitize=address %t && ./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; } .. code-block:: text ==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 Stack-buffer-overflow ^^^^^^^^^^^^^^^^^^^^^ .. code-block:: c // RUN: clang -O -g -fsanitize=address %t && ./a.out int main(int argc, char **argv) { int stack_array[100]; stack_array[1] = 0; return stack_array[argc + 100]; // BOOM } .. code-block:: text ==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 Global-buffer-overflow ^^^^^^^^^^^^^^^^^^^^^^ .. code-block:: c // RUN: clang -O -g -fsanitize=address %t && ./a.out int global_array[100] = {-1}; int main(int argc, char **argv) { return global_array[argc + 100]; // BOOM } .. code-block:: text ==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 References ---------- * `Wikipedia `_ * `Clang documentation`_ .. _Clang documentation: https://clang.llvm.org/docs