linux-kernel - Re: [PATCH] module: exclude SHN_UNDEF symbols from kallsyms api

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] [day] [month] [year] [list]

Date:   Tue, 5 Jun 2018 08:57:01 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Jessica Yu <jeyu@...nel.org>
Cc:     linux-kernel@...r.kernel.org, live-patching@...r.kernel.org
Subject: Re: [PATCH] module: exclude SHN_UNDEF symbols from kallsyms api

On Tue, Jun 05, 2018 at 10:42:23AM +0200, Jessica Yu wrote:
> Livepatch modules are special in that we preserve their entire symbol
> tables in order to be able to apply relocations after module load. The
> unwanted side effect of this is that undefined (SHN_UNDEF) symbols of
> livepatch modules are accessible via the kallsyms api and this can
> confuse symbol resolution in livepatch (klp_find_object_symbol()) and
> cause subtle bugs in livepatch.
> 
> Have the module kallsyms api skip over SHN_UNDEF symbols. These symbols
> are usually not available for normal modules anyway as we cut down their
> symbol tables to just the core (non-undefined) symbols, so this should
> really just affect livepatch modules. Note that this patch doesn't
> affect the display of undefined symbols in /proc/kallsyms.
> 
> Reported-by: Josh Poimboeuf <jpoimboe@...hat.com>
> Tested-by: Josh Poimboeuf <jpoimboe@...hat.com>
> Signed-off-by: Jessica Yu <jeyu@...nel.org>

Reviewed-by: Josh Poimboeuf <jpoimboe@...hat.com>

-- 
Josh