kernel-hardening - Re: [PATCH v2 01/28] x86/boot/compressed: Disable relocation relaxation

Follow @Openwall on Twitter for new release announcements and other news

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

Message-ID: <20200903234215.GA106172@rani.riverdale.lan>
Date: Thu, 3 Sep 2020 19:42:15 -0400
From: Arvind Sankar <nivedita@...m.mit.edu>
To: Kees Cook <keescook@...omium.org>
Cc: Sami Tolvanen <samitolvanen@...gle.com>,
	Masahiro Yamada <masahiroy@...nel.org>,
	Will Deacon <will@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	clang-built-linux@...glegroups.com,
	kernel-hardening@...ts.openwall.com, linux-arch@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kbuild@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	x86@...nel.org, Arvind Sankar <nivedita@...m.mit.edu>
Subject: Re: [PATCH v2 01/28] x86/boot/compressed: Disable relocation
 relaxation

On Thu, Sep 03, 2020 at 02:44:41PM -0700, Kees Cook wrote:
> On Thu, Sep 03, 2020 at 01:30:26PM -0700, Sami Tolvanen wrote:
> > From: Arvind Sankar <nivedita@...m.mit.edu>
> > 
> > Patch series [4] is a solution to allow the compressed kernel to be
> > linked with -pie unconditionally, but even if merged is unlikely to be
> > backported. As a simple solution that can be applied to stable as well,
> > prevent the assembler from generating the relaxed relocation types using
> > the -mrelax-relocations=no option. For ease of backporting, do this
> > unconditionally.
> > 
> > [0] https://gitlab.com/x86-psABIs/x86-64-ABI/-/blob/master/x86-64-ABI/linker-optimization.tex#L65
> > [1] https://lore.kernel.org/lkml/20200807194100.3570838-1-ndesaulniers@google.com/
> > [2] https://github.com/ClangBuiltLinux/linux/issues/1121
> > [3] https://reviews.llvm.org/rGc41a18cf61790fc898dcda1055c3efbf442c14c0
> > [4] https://lore.kernel.org/lkml/20200731202738.2577854-1-nivedita@alum.mit.edu/
> > 
> > Reported-by: Nick Desaulniers <ndesaulniers@...gle.com>
> > Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
> 
> Reviewed-by: Kees Cook <keescook@...omium.org>
> 
> -- 
> Kees Cook

Note that since [4] is now in tip, assuming it doesn't get dropped for
some reason, this patch isn't necessary unless you need to backport this
LTO series to 5.9 or below.

Thanks.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.