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#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "bar.h"
extern void foo(unsigned int *);
void bar(char *ptr) {
if (((uintptr_t)ptr >> 56) != 0x1f) {
fprintf(stderr, "Top byte corrupted on Rust -> C FFI boundary!\n");
exit(1);
}
}
int main(void)
{
// Construct a pointer with an arbitrary tag in bits 56-59, simulating an MTE tag.
// It's only necessary that the tag is preserved across FFI bounds for this test.
unsigned int *ptr;
ptr = alloc_page();
if (ptr == MAP_FAILED)
{
perror("mmap() failed");
return EXIT_FAILURE;
}
// Store an arbitrary tag in bits 56-59 of the pointer (where an MTE tag may be),
// and a different value in the ignored top 4 bits.
ptr = (unsigned int *)((uintptr_t)ptr | 0x1fl << 56);
if (mte_enabled()) {
set_tag(ptr);
}
ptr[0] = 61;
ptr[1] = 62;
foo(ptr); // should change the contents of the page to start with 0x63 0x64 and call `bar`
if (ptr[0] != 0x63 || ptr[1] != 0x64) {
fprintf(stderr, "invalid data in memory; expected '63 64', got '%d %d'\n", ptr[0], ptr[1]);
return EXIT_FAILURE;
}
return 0;
}
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