linux-kernel - Re: [PATCH 2/4] kaslr: check if the random addr is available

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 10 Sep 2014 21:55:55 +0800
From:	Baoquan He <bhe@...hat.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Kees Cook <keescook@...omium.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andi Kleen <ak@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Deutschmann <whissi@...ssi.de>,
	Dave Young <dyoung@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	WANG Chao <chaowang@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 2/4] kaslr: check if the random addr is available

On 09/09/14 at 03:41pm, Vivek Goyal wrote:
> On Sat, Sep 06, 2014 at 06:16:57AM +0800, Baoquan He wrote:
> 
> [CC hpa ]
> 
> > Hi Kees,
> > 
> > Yes, process_e820_entry() can make sure the choice+output_len <
> > CONFIG_RANDOMIZE_BASE_MAX_OFFSET, but that can't stop other bootloaders
> > to put kernel in region above CONFIG_RANDOMIZE_BASE_MAX_OFFSET.
> > 
> > E.g in kdump, we can set crashkernel=256M@...4M in cmdline. Then the 1st
> > kernel will reserve 256M memory just at 1024M place. So if load kdump
> > kernel now, the output will be 1024M before choose_kernel_location().
> > With this value, output won't be changed in choose_kernel_location(),
> > then it will do decompress(), then call handle_relocations(). Then since
> > 1024 is not equal to LOAD_PHYSICAL_ADDR, it will start relocatoins
> > handling. And this cause _text stamping into MODULES vaddr range. System
> > will be exceptional.
> 
> Bao,
> 
> If you apply your first patch where output_orig == output, then
> handle_relocations() will not do anything for x86_64 case and bail
> out. That should take care of this issue. Isn't it? And we should
> not require this patch.

Yes, exactly.

> 
> Thanks
> Vivek
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/