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Using heap memory as the stack in C (little experiment on amd64 in C)
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| #include <stdlib.h> | |
| #include <stdio.h> | |
| #include <stdint.h> | |
| __attribute__((noinline)) | |
| void _main() { | |
| int troll; | |
| printf("sussy, %p\n", &troll); | |
| } | |
| static uint64_t old_sp; | |
| int main() { | |
| register volatile uint64_t rsp asm("rsp"); | |
| old_sp = rsp; | |
| void *new_stack = malloc(33554432); | |
| if (!new_stack) { | |
| printf("Failed to allocate new stack\n"); | |
| return -1; | |
| } | |
| volatile void *new_sp = new_stack + 33554432; | |
| asm volatile("movq %0, %%rsp" | |
| :: "r" (new_sp) | |
| ); | |
| _main(); | |
| asm volatile("movq %0, %%rsp" | |
| :: "r" (old_sp) | |
| ); | |
| free(new_stack); | |
| printf("stack @ %p retained, with new sp @ %p!\n", old_sp, new_sp); | |
| } |
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