linux-kernel - 32-bit x86 system reboots automatically on resume from hibernate (ASLR issue?)

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Message-ID: <58D13084.7040800@yandex.ru>
Date:   Tue, 21 Mar 2017 16:54:12 +0300
From:   Evgenii Shatokhin <eugene.shatokhin@...dex.ru>
To:     Kees Cook <keescook@...omium.org>
Cc:     "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: 32-bit x86 system reboots automatically on resume from hibernate
 (ASLR issue?)

Hi,

One of my x86 machines with a 32-bit Linux system (ROSA Linux in this 
case) automatically reboots when it tries to resume from hibernate. This 
happens shortly after "Image loading progress 100%" message is shown on 
the screen.

No traces of the error are in the system log after reboot though.

The problem is present at least in the mainline kernels 4.8 - 4.10. With 
earlier versions (I tried 4.4, 4.5, etc.), the system resumes OK.

The bisection pointed to the following commit as the first "bad" one:

commit 65fe935dd2387a4faf15314c73f5e6d31ef0217e
Author: Kees Cook <keescook@...omium.org>
Date:   Mon Jun 13 15:10:02 2016 -0700

     x86/KASLR, x86/power: Remove x86 hibernation restrictions

Hardware: https://linux-hardware.org/index.php?probe=e6a06c64c7
Config used to build the kernel at rev. 65fe935: 
http://pastebin.com/AxEA6ahb

If I understand it correctly, this commit just enabled ASLR by default 
regardless of whether hibernation support was present or not. Before 
this commit, ASLR was disabled on that system because hibernation was 
supported.

To check if ASLR is really involved here, I rebuilt the kernel with 
CONFIG_RANDOMIZE_BASE unset - now the system resumes OK from 
hibernation, no auto reboots, no other visible problems so far.

The problem does not show up in a 64-bit Linux system installed on the 
same machine. Only the 32-bit system is affected.

Regards,
Evgenii