linux-kernel - Re: [PATCH] tracing: fix va_list breakage in trace_check

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: <20211118093032.31c06b11@gandalf.local.home>
Date:   Thu, 18 Nov 2021 09:30:32 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Nikita Yushchenko <nikita.yushchenko@...tuozzo.com>
Cc:     Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        kernel@...nvz.org
Subject: Re: [PATCH] tracing: fix va_list breakage in trace_check_vprintf()

On Thu, 18 Nov 2021 07:57:33 +0300
Nikita Yushchenko <nikita.yushchenko@...tuozzo.com> wrote:

> What I don't like here is - trace_check_vprintf() will still extract wrong positional arguments, and use 
> the result as part of it's logic.
> 
> Although with your change such use becomes a no-op, this is unintuitive and can turn easily into real 
> problems with future changes.

That trace_check_vprintf() is just full of unintuitive logic ;-)

Which is why I prefer to keep any remnants of that code in that code and
not spread it around. 

> 
> And, the above comment is inexact...  why we can't test? We can, testing code does no depend on 
> iter->seq. What we can't is - reliably extract str to test.
> 
> If testing seq->full condition is preferred over forcibly consuming args from va_list, then such a test 
> shall be done before trace_check_vprintf() tries to use va_arg(). Will submit a patch doing that.

I'm happy with that patch, but can you please resend it as a top level
patch and not a reply, otherwise my patchwork doesn't catch it and my
scripts will not work on it.

Thanks,

-- Steve