elf64 value out of range

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funggong

Joined: 08 Nov 2016
Posts: 6

funggong 08 Nov 2016, 08:46

Code:

format elf64 executable at 0x4000000000 as 'sys'
start:
cmp rdi,start

cmp rdi,start
error: value out of range.

anyone can tell me why this happened?

08 Nov 2016, 08:46

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20631
Location: In your JS exploiting you and your system

revolution 08 Nov 2016, 08:51

The cmp instruction cannot support large immediate values >=2^31. It is a limitation of the x86-64 CPU.

To fix this you can use either lea for RIP relative offsets to "start", or use mov to get the absolute address (but this makes your code non-relocatable).

Last edited by revolution on 08 Nov 2016, 08:55; edited 1 time in total

08 Nov 2016, 08:51

funggong

Joined: 08 Nov 2016
Posts: 6

funggong 08 Nov 2016, 09:05

revolution wrote:

The cmp instruction cannot support large immediate values >=2^31. It is a limitation of the x86-64 CPU.

To fix this you can use either lea for RIP relative offsets to "start", or use mov to get the absolute address (but this makes your code non-relocatable).

thank you very much.

08 Nov 2016, 09:05

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