Question

我正在尝试实现一个链接列表，它会在遇到调用/返回汇编指令时存储内存地址。这通过解析程序集的每一行来递归地工作，并且在遇到调用或返回指令时仅断开函数。到目前为止，这适用于调用指令，这意味着返回地址被保存在链接列表中的节点，但是当在返回指令期间尝试检索此值时，数据已丢失（意味着链接列表现在为空）。以下是我的工作内容：

struct ret_addr {
    int address;
    struct ret_addr *nxt;
};

struct ret_addr *ret_data(cs_insn *insn, struct ret_addr **head) {
    struct ret_addr *r = malloc(sizeof(*r));
    r->address = insn->address + insn->size;
    r->nxt = (*head);
    (*head) = r;
    return r;
}

struct bb_data *disassemble_function_cfg(int startAddr, unsigned char *bytes, int end_section) {
    csh handle;
    cs_insn *insn;
    cs_detail *detail;
    cs_x86 *x86;
    size_t count;
    int stop_disasm = 0;
    struct bb_data *edges = NULL;
    struct ret_addr *ret_edge = NULL;

    count = cs_disasm(handle, bytes, end_section, startAddr, 1, &insn);

    detail = insn->detail;
    for(int n = 0; n < detail->groups_count; n++) {

        //break when encountering a call instruction
        if(detail->groups[n] == X86_GRP_CALL) {
            stop_disasm = 1;
            vector_new(edges);
            edges = call_insn(handle, x86, insn, vector_back(edges));
            ret_edge = ret_data(insn, &ret_edge);
        }

        //break when encountering a return instruction
        else if(detail->groups[n] == X86_GRP_RET) {
            stop_disasm = 1;
            vector_new(edges);
            edges = ret_insn(insn, edges, &ret_edge);
        }

    }

    if(!stop_disasm) {
        disassemble_function_cfg(insn->address + insn->size, bytes + insn->size, end_section);
    }
    else {
        return edges;
    }
}

Answer 1

您不会在递归调用之间保留列表。你可能想做什么：

struct bb_data *disassemble_function_cfg(struct ret_addr **ret_edge, int startAddr, unsigned char *bytes, int end_section)
{
   ...
   if(*ret_edge == NULL) *ret_edge = ret_data(insn, ret_edge);
   ...
}

链接列表不会在递归函数调用中保留值？

1 个答案: