int
main(int argc, char **argv) {
void *faddr = strxfrm;
void *paddr = (void*) ((u_int32_t)faddr & 0xfffff000);
if(mprotect(paddr, 4096, PROT_READ|PROT_WRITE|PROT_EXEC) >= 0) {
((u_char *)faddr)[0] = 0xcc;
strxfrm("foo", "", 0);
} else
perror("mprotect");
exit(0);
}
$ ./mp
Trace/BPT trap
The simplest answer to your question that jumps into my head is "relocations", but I'm always surprised by the everyday craziness of the C runtime and the Unix ABI, so I'm sure there's a simpler answer.
