Source:

 
#include  
#include  
#include  
Void func (int key) {
Char overflowme [32]. 
Printf (" overflow me: "); 
Gets (overflowme);//smash me! 
If (key==0 xcafebabe) {
System ("/bin/sh "); 
} 
The else {
Printf (" Nah.. \n"); 
} 
} 
Int main (int arg c, char * argv []) {
Func (0 xdeadbeef); 
return 0; 
} 

GCC - S get assembly code

 
The file "PWN. C 
". Section. Rodata 
LC0: 
The string "overflow me: 
"LC1: 
The string "/bin/sh 
"LC2: 
The string "nah.. "
The text 
. Globl func 
The func, @ function 
Func: 
LFB2: 
. Cfi_startproc 
RBP pushq % 
16. Cfi_def_cfa_offset 
. Cfi_offset 6-16 
RSP movq %, % RBP 
6. Cfi_def_cfa_register 
RSP subq at $64, % 
Movl % edi, - 52 (RBP) % 
Movq % fs: 40, % rax 
RBP movq % rax - 8 (%) 
Xorl % eax and % eax 
Movl $. LC0, % edi 
Movl $0, % eax 
Call printf 
Leaq - 48 (RBP) %, % rax 
Rax movq %, % rdi 
Movl $0, % eax 
The call gets 
RBP CMPL $- 889275714-52 (%) 
Developed. The L2 
Movl $. LC1, % edi 
Call system 
JMP. L5 
L2: 
Movl $. LC2, % edi 
Call the puts 
L5: 
The nop 
Movq - 8 (RBP) %, % rax 
Xorq % fs: 40, % rax 
Je. L4 
Call __stack_chk_fail 
L4: 
Leave 
. Cfi_def_cfa 7, 8 
Ret 
. Cfi_endproc 
LFE2: 
. The size func,. - func 
. Globl main 
The main, @ function 
Main: 
LFB3: 
. Cfi_startproc 
RBP pushq % 
16. Cfi_def_cfa_offset 
. Cfi_offset 6-16 
RSP movq %, % RBP 
6. Cfi_def_cfa_register 
Subq $16, % RSP 
Movl % edi, 4 (RBP) % 
Movq % rsi, - 16 (RBP) % 
Movl $- 559038737, % edi 
Call func 
Movl $0, % eax 
Leave 
. Cfi_def_cfa 7, 8 
Ret 
. Cfi_endproc 
LFE3: 
.. The size, the main - the main 
Is "the ident GCC: (Ubuntu 5.4.0-6 ubuntu1 ~ 16.04.12) 5.4.0 20160609" 
. Section. Note. The GNU - stack, ", "@ progbits 

Beginners, will learn little by little and bit by bit after analysis here below in some detail, interested can post their own understanding and analysis of oh,

CodePudding user response:

Can suggest using VS6, inside the assembly code and C code, at the same time to facilitate learning, sentence by sentence
Beginners assembly language, can from the if - else, function calls,

CodePudding user response:

reference 1st floor proorck2019 response:

suggested VS6, inside the assembly code can and C code, at the same time to facilitate learning, sentence by sentence
Beginners assembly language, can from the if - else, function calls,

do you mean in vs6 see each corresponding assembler c statement? If so, there are similar under the Ubuntu?

CodePudding user response:

. Cfi_def_cfa_offset modifies a rule for computing the CFA. Register remains the same, but offset is new. Note that it is the absolute offset that will be added to a defined Register to compute the CFA address.
Cfi_offset register, offset

Previous value of the register is saved at offset offset from CFA.

https://sourceware.org/binutils/docs/as/CFI-directives.html#CFI-directives

CodePudding user response:

Can use godbolt (online) or IDA (local) software,

CodePudding user response:

reference 4 floor apkipa1 response:

can use godbolt (online) or IDA (local) software,

godbolt sounds good, thanked the first

CodePudding user response:

I hope it can help you: https://blog.csdn.net/it_xiangqiang/category_10581430.html
I hope it can help you: https://blog.csdn.net/it_xiangqiang/category_10768339.html