linux-kernel - Re: [PATCH 2/5] trace-cmd: Fix NULL pointer being passed to memcpy

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Message-ID: <20171009183359.3267a870@gandalf.local.home>
Date:   Mon, 9 Oct 2017 18:33:59 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Michael Sartain <mikesart@...tmail.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] trace-cmd: Fix NULL pointer being passed to memcpy

On Mon, 9 Oct 2017 16:27:10 -0600
Michael Sartain <mikesart@...tmail.com> wrote:

> > > -	memcpy(option->data, data, size);
> > > +
> > > +	/* Some IDs (like TRACECMD_OPTION_TRACECLOCK) pass NULL data */
> > > +	if (data)
> > > +		memcpy(option->data, data, size);  
> > 
> > Is this a problem, as when this happens, size should be zero. Does it
> > crash with data=NULL and size=0, or have you seen size not be zero?  
> 
> I got an ASAN warning, but you are correct - the size was 0 and it did
> not crash.

OK, but it's almost like dividing zero from zero. Can you send another
patch, but this time check if (size) instead of if (data).

-- Steve