You may be deeply aware that when using the DIV/IDIV directive, running the program often inexplicably pop-up "the program to perform illegal operation" error, usually "division overflow", but your code may be as follows:
MOV eax,1000
Cwd
Div CX
Generally after using the CWD command, it can be normal, but very unstable, I feel strange, why this?
Huitiansou's Answer:
Yes: "About the use of Div/idiv/mul/imul directives by AoGo" causes a bug
That's because the divisor reached the double value,
So it can't be extended with symbols,
and can only send a high of 16 digits 0
All we have to do is make sure that edx is 0, and that this method is recommended when running 32-digit division, and absolutely not illegal operations (except for 0/overflow, of course).
Example:
XOR Edx,edx
MOV eax,6527363
MOV ecx,28732
div ECX
All you have to do is remove the above XOR Edx,edx command to ensure 100% illegal operation.
Also, multiplication instructions can do this. can be guaranteed to be more secure.
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