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Date: Fri, 11 Nov 2016 19:13:03 +0100
From: Petr Mladek <pmladek@suse.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Joe Perches <joe@perches.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Chris Mason <clm@fb.com>, Josef Bacik <jbacik@fb.com>,
        David Sterba <dsterba@suse.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/4] printk/kdb: Handle more message headers
Message-ID: <20161111181302.GB2145@dhcp128.suse.cz>
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On Fri 2016-11-11 12:35:13, Steven Rostedt wrote:
> On Wed,  9 Nov 2016 13:41:29 +0100
> Petr Mladek <pmladek@suse.com> wrote:
> 
> > diff --git a/include/linux/printk.h b/include/linux/printk.h
> > index eac1af8502bb..a0859e169bc3 100644
> > --- a/include/linux/printk.h
> > +++ b/include/linux/printk.h
> > @@ -31,6 +31,14 @@ static inline const char *printk_skip_level(const char *buffer)
> >  	return buffer;
> >  }
> >  
> > +static inline const char *printk_skip_headers(const char *buffer)
> > +{
> > +	while (printk_get_level(buffer))
> > +		buffer = printk_skip_level(buffer);
> 
> Hmm, shouldn't there be a length passed in here. What happens if buffer
> ends with a header. Can't this overflow?

It is OK when the string has the trailing '\0'. This is the case here.

Note that printk_skip_level() and printk_get_level() would have the
same problem if only the first byte of the header fit the buffer.

Best Regards,
Petr