在使用asan的时候，如果我们想关闭/取消：useafterpoision 检测

使用这个allow_user_poisoning=0，来取消

以这个例子为例：

// example1.cpp
// use-after-poison error
#include <stdlib.h>

extern "C" void __asan_poison_memory_region(void *, size_t);

int main(int argc, char **argv) {
    char *x = new char[16];
    x[10] = 0;
    __asan_poison_memory_region(x, 16);

    int res = x[argc * 10];              // Boom!
 
    delete [] x;
    return res;
}

gcc -fsanitize=address  eaxmple1.cpp -o ufpexe

运行会报错：

=================================================================
==9369==ERROR: AddressSanitizer: use-after-poison on address 0x60200000001a at pc 0x5635fbfa99f2 bp 0x7fffc5a981d0 sp 0x7fffc5a981c0
READ of size 1 at 0x60200000001a thread T0
    #0 0x5635fbfa99f1 in main (/home/xijun.gong/x86_64-linux-rel/tops/system_test/model_test/topsinference_test/a.out+0x9f1)
    #1 0x7f5e429f5bf6 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21bf6)
    #2 0x5635fbfa9859 in _start (/home/xijun.gong/x86_64-linux-rel/tops/system_test/model_test/topsinference_test/a.out+0x859)

0x60200000001a is located 10 bytes inside of 16-byte region [0x602000000010,0x602000000020)
allocated by thread T0 here:
    #0 0x7f5e42ea5608 in operator new[](unsigned long) (/usr/lib/x86_64-linux-gnu/libasan.so.4+0xe0608)
    #1 0x5635fbfa9952 in main (/home/xijun.gong/x86_64-linux-rel/tops/system_test/model_test/topsinference_test/a.out+0x952)
    #2 0x7f5e429f5bf6 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x21bf6)

SUMMARY: AddressSanitizer: use-after-poison (/home/xijun.gong/x86_64-linux-rel/tops/system_test/model_test/topsinference_test/a.out+0x9f1) in main
Shadow bytes around the buggy address:
  0x0c047fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c047fff8000: fa fa f7[f7]fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8050: 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
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==9369==ABORTING

这样运行会取消掉：

ASAN_OPTIONS=allow_user_poisoning=0  ./exeamp