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Date: Sun, 20 Nov 2016 10:12:32 +0800
From: zerons <zeronsaxm@...il.com>
To: kernel-hardening@...ts.openwall.com
Subject: Re: get NULL pointer dereferences or #GP fault to
infomation leakage
If kernel panic on oops, then NULL pointer deref and others may cause a DoS.
Maybe restrict user access to dmesg and other log files so that unprivileged
users couldn't read log messages, or something like /proc/kallsyms(output 0000
if no permission). Then those faults stll be useless.
On 11/20/2016 12:36 AM, Thomas Garnier wrote:
> It is an issue because having KASLR enable without panic on oops is not
> really useful. Same apply to other mitigations that rely on randomness.
>
> On Sat, Nov 19, 2016 at 3:50 AM, zerons <zeronsaxm@...il.com> wrote:
>
>> I wonder if this could be an issue.
>>
>> Test on Ubuntu 16.04 with linux kernel 4.4.x, x86_64.
>>
>> When a NULL-pointer-deref or a #GP fault
>> (e.g: access to 0xdead0000-xxxxxxxx) happens in kernel space,
>> it seems that the kernel would kill the current process, then
>> output the Oops message or "general protection fault" message.
>>
>> So we can get these messages via `dmesg` or reading the /var/log/...
>>
>> I think this may be a way to bypass the KASLR, could it be?
>>
>
>
>
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