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Index > Unix > FreeBSD and ELF GNU_STACK segment readable

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MaoKo



Joined: 07 May 2019
Posts: 36
Location: Paris/French
MaoKo
Hello!! I think there is a problem with read only stack in FreeBSD.
On my machine the OS literally hangup. I can't shutdown it properly.
Even with this simple snippet:
Code:
format ELF64 executable $09
entry _start
segment executable readable
_start:
  mov rax, $01
  xor rdi, rdi
  syscall
segment gnustack readable
    

This seem to also affect 32-bits binary. My FreeBSD is currently at version 12.0.
But I've tested on 11.2 and the system hang too when I try to reboot it.
If anyone known about this. Hope this might help Smile.
Post 11 Dec 2019, 04:25
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17011
Location: In your JS exploiting you and your system
revolution
I think it should be reported to the FreeBSD devs.
Post 11 Dec 2019, 04:28
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MaoKo



Joined: 07 May 2019
Posts: 36
Location: Paris/French
MaoKo
Yes you are right. But I'm not sure if it's really a bug. And read only stack segment is not easily generated by gcc/clang. I try to prevent fasm user of this. But yeah, I will try to report this as soon as possible Smile.
Post 11 Dec 2019, 04:36
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17011
Location: In your JS exploiting you and your system
revolution
It looks like a bug to me. It shouldn't be possible for a user program to create a denial-of-service (aka a hang) for the entire system.
Post 11 Dec 2019, 04:41
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guignol



Joined: 06 Dec 2008
Posts: 666
guignol
Laughing
Post 11 Dec 2019, 11:51
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