组装jmp到不存在的行 [英] assembly jmp to a line that doesn't exist

问题描述

对于显示"jmpq * 0x400850"的行，实际上没有这样的行具有0x400850.在这种情况下，由于我无法跳到提到的地方，我是否只跳过此命令并转到下一行中的命令?

For the line that says "jmpq *0x400850", there is actually no such line has 0x400850. In this case, since I cannot jump to the place that it is mentioned, do I just skip this command and go to the command that is in the line below?

所以答案告诉我在终端中键入"objdump"，所以我键入了

So the answers told me to type "objdump" in terminal, so I typed

    objdump -d ./bin-lab-ref > output.txt

，终端上没有输出. 在这种情况下我该怎么办?

and I got no output in the terminal. What should I do in this situation?

推荐答案

指令jmpq *0x400850(,%rax,8)跳转到存储在地址0x400850(,%rax,8)上的值，而不是跳转到地址0x400850(,%rax,8)本身.可能在此地址处有一个跳转表，并且rax从跳转表中选择一个条目以跳转到.

The instruction jmpq *0x400850(,%rax,8) jumps to the value stored at address 0x400850(,%rax,8), not to the address 0x400850(,%rax,8) itself. Likely, there is a jump table at this address and rax selects an entry from the jump table to jump to.

检查0x400850周围的内存，以查找跳转表具有的条目以及跳转的位置.您可以使用objdump -s转储可执行文件的映像.

Inspect the memory around 0x400850 to find out what entries the jump table has and thus where the jump goes. You can get a dump of the executable's image using objdump -s.

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