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"На соревновании Pwn2Own 2019 продемонстрированы взломы Firef..." Отправлено Аноним84701, 22-Мрт-19 22:47
Так как пятница, да и самому стало интересно, наовноко^W набросал по быстрому макет: % gcc8 -Wall -Wextra -std=c11 -g -O3 overflow.c -o overflow % cat overflow.c #include <stdio.h> #include <stdlib.h> #include <stdint.h> int main(int argc , char* argv[argc +1]) {     if (argc < 3) return EXIT_FAILURE;          int64_t x = strtol(argv[1], NULL, 10);     int64_t y = strtol(argv[2], NULL, 10);     while (x > y) {x += 0xFFFFFFF;}     printf("result %ld\n",x);     return EXIT_SUCCESS; } % time ./overflow 4 2 result -9223372036586340477 ./overflow 4 2  30,27s user 0,01s system 99% cpu 30,295 total % time ./overflow 4 2 result -9223372036586340477 ./overflow 4 2  30,00s user 0,00s system 99% cpu 30,041 total и % cat overflow_checked.c #include <stdio.h> #include <stdlib.h> #include <stdint.h> int main(int argc , char* argv[argc +1]) {     if (argc < 3) return EXIT_FAILURE;          int64_t x = strtol(argv[1], NULL, 10);     int64_t y = strtol(argv[2], NULL, 10);     while (x > y) {         if (__builtin_add_overflow(x, 0xFFFFFFF, &x)){                 printf("overflow detected %ld\n", x);                 break;         }     }     printf("result %ld\n",x);     return EXIT_SUCCESS; } % gcc8 -Wall -Wextra -std=c11 -g -O3 overflow_checked.c -o overflow_checked % time ./overflow_checked 4 2 overflow detected -9223372036586340477 result -9223372036586340477 ./overflow_checked 4 2  30,63s user 0,00s system 99% cpu 30,662 total % time ./overflow_checked 4 2 overflow detected -9223372036586340477 result -9223372036586340477 ./overflow_checked 4 2  29,79s user 0,00s system 99% cpu 29,835 total