linux-kernel - Re: [PATCH] debug: fix WARN_ON

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]

Message-ID: <20170715132634.w4ytbyidwpb5zzsp@treble>
Date:   Sat, 15 Jul 2017 08:26:34 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Mike Galbraith <efault@....de>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] debug: fix WARN_ON_ONCE() for modules

On Sat, Jul 15, 2017 at 08:29:57AM +0200, Mike Galbraith wrote:
> On Sat, 2017-07-15 at 00:10 -0500, Josh Poimboeuf wrote:
> > 
> > The bug table was made writable for vmlinux, which relies on
> > vmlinux.lds.S and vmlinux.lds.h for laying out the sections.  However,
> > it wasn't made writable for modules, which rely on the ELF section
> > header flags.
> 
> It seems vmlinux sort of relies on your fix too.  objdump did show
> vmlinux __bug_table as being READONLY, but that (lie) is now gone.

Yeah, those ELF bits are ignored by the kernel.  It sets its own
protections during boot, e.g. mark_rodata_ro().

-- 
Josh