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From: "Du, Changbin" <changbin.du@intel.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Du, Changbin" <changbin.du@intel.com>,
	jolsa@redhat.com, peterz@infradead.org, mingo@redhat.com,
	alexander.shishkin@linux.intel.com, linux-kernel@vger.kernel.org,
	linux-perf-users@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH 2/3] tracing: make sure the parsed string always terminates with '\0'
Date: Mon, 15 Jan 2018 18:49:50 +0800	[thread overview]
Message-ID: <20180115104950.u33gj7h4of7mlekx@intel.com> (raw)
In-Reply-To: <20180109231022.5e9ca245@vmware.local.home>

On Tue, Jan 09, 2018 at 11:10:22PM -0500, Steven Rostedt wrote:
> On Wed, 10 Jan 2018 11:02:06 +0800
> "Du, Changbin" <changbin.du@intel.com> wrote:
> 
> > On Tue, Jan 09, 2018 at 06:02:58PM -0500, Steven Rostedt wrote:
> > > On Tue,  9 Jan 2018 17:55:47 +0800
> > > changbin.du@intel.com wrote:
> > >   
> > > > From: Changbin Du <changbin.du@intel.com>
> > > > 
> > > > The parser parse every string into parser.buffer. And some of the callers
> > > > assume that parser.buffer contains a C string. So it is dangerous that the
> > > > parser returns a unterminated string. The userspace can leverage this to
> > > > attack the kernel.  
> > > 
> > > Is this only a bug if we apply your first patch?
> > >  
> > I don't think so. Seems it is there already.
> >  
> 
> OK. I'll have to take a deeper look into this so that I completely
> understand the problem and your solution. I'm currently traveling and
> may not get to do that this week. Please ping me next week if you don't
> hear back from me on this issue.
> 
> Thanks!
> 
> -- Steve

I checked every trace_get_user() clients again and found it is not an issue in
current kernel. The client has checked trace_parser_cont() before using parsed
string or append '\0'.

I still want to make the parser returns a '\0' terminated string. Then we don't
require the clients append it. I think this would be better since we are dealing
with strings.

-- 
Thanks,
Changbin Du

  reply	other threads:[~2018-01-15 10:58 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-09  9:55 [PATCH 0/3] tracing: Fix the parser when processing strings w/ or w/o terminated '\0' changbin.du
2018-01-09  9:55 ` [PATCH 1/3] tracing: detect the string termination character when parsing user input string changbin.du
2018-01-09 22:54   ` Steven Rostedt
2018-01-10  3:01     ` Du, Changbin
2018-01-10  4:09       ` Steven Rostedt
2018-01-09  9:55 ` [PATCH 2/3] tracing: make sure the parsed string always terminates with '\0' changbin.du
2018-01-09 23:02   ` Steven Rostedt
2018-01-10  3:02     ` Du, Changbin
2018-01-10  4:10       ` Steven Rostedt
2018-01-15 10:49         ` Du, Changbin [this message]
2018-01-09  9:55 ` [PATCH 3/3] tracing: don't set parser->cont if it has reached the end of input buffer changbin.du
2018-01-09 23:12   ` Steven Rostedt
2018-01-10  3:18     ` Du, Changbin
2018-01-10  4:19       ` Steven Rostedt
2018-01-12  4:05         ` Du, Changbin
2018-01-12 15:31           ` Steven Rostedt
2018-01-14  5:43             ` Du, Changbin

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