linux-kernel - Re: [PATCH v8 08/14] livepatch: only match unique symbols when using FG-KASLR

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Message-ID: <20211206060350.f4hqug2jhgjlaw3c@treble>
Date:   Sun, 5 Dec 2021 22:03:50 -0800
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        linux-hardening@...r.kernel.org, x86@...nel.org,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Kristen Carlson Accardi <kristen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        Miklos Szeredi <miklos@...redi.hu>,
        Ard Biesheuvel <ardb@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Bruce Schlobohm <bruce.schlobohm@...el.com>,
        Jessica Yu <jeyu@...nel.org>,
        kernel test robot <lkp@...el.com>,
        Miroslav Benes <mbenes@...e.cz>,
        Evgenii Shatokhin <eshatokhin@...tuozzo.com>,
        Jonathan Corbet <corbet@....net>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Marios Pomonis <pomonis@...gle.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-arch@...r.kernel.org, live-patching@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: Re: [PATCH v8 08/14] livepatch: only match unique symbols when using
 FG-KASLR

On Fri, Dec 03, 2021 at 11:05:54AM +0100, Peter Zijlstra wrote:
> On Thu, Dec 02, 2021 at 11:32:08PM +0100, Alexander Lobakin wrote:
> > If any type of function granular randomization is enabled, the sympos
> > algorithm will fail, as it will be impossible to resolve symbols when
> > there are duplicates using the previous symbol position.
> > 
> > We could override sympos to 0, but make it more clear to the user
> > and bail out if the symbol is not unique.
> 
> Since we're going lots of horrendous things already, why can't we fix
> this duplicate nonsense too?

I assume you mean using this new linker flag: "-z unique-symbol"

https://sourceware.org/bugzilla/show_bug.cgi?id=26391

-- 
Josh