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| // The following code examines multiple routines of definining dynamic buffers in C. | |
| // This file fires a runtime malloc() error due to a HEAP corruption error; because of buffer overflow. | |
| // Two maneuvers are introduced to fix this | |
| #include <stdio.h> | |
| #include <stdlib.h> | |
| int main() { | |
| // buffers | |
| const char *value1 = "Hi"; | |
| const char *value2 = "Hello\n Dynamic Buffers!"; | |
| // pointer to buffers | |
| const char **inputs = malloc(sizeof(char *)); | |
| // automatic allocation of address buffer ??? | |
| // appends new addresses to the buffer automatically! | |
| *inputs = value1; | |
| *(inputs + 1) = value2; | |
| *(inputs + 2) = value1; | |
| *(inputs + 3) = value1; | |
| *(inputs + 4) = value1; | |
| // printf("%s\n", ((const char*) inputs[2])); | |
| // printf("%s\n", ((const char*) inputs[2])); | |
| free((void *) inputs); | |
| return 0; | |
| } |
The following is a board summary to the 3 solutions presented here (incl. the defective solution that introduces memory access violations):
For more, follow the GNU Libc documentation for heap manipulating algorithms.
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Caution
This solution introduces a memory access violation, and forceful write memory corruption, as debugged by Valgrind (see the invalid R/W on pre-allocated blocks!):
Valgrind memory debug: