linux-kernel - Re: [PATCH 2/2] tracing: Use strncpy instead of memcpy for string keys in hist triggers

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Date:   Mon, 4 Mar 2019 16:56:53 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Tom Zanussi <zanussi@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH 2/2] tracing: Use strncpy instead of memcpy for string
 keys in hist triggers

On Mon, 4 Mar 2019 16:50:00 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> > +++ b/kernel/trace/trace_events_hist.c
> > @@ -4695,9 +4695,10 @@ static inline void add_to_key(char *compound_key, void *key,
> >  		/* ensure NULL-termination */
> >  		if (size > key_field->size - 1)
> >  			size = key_field->size - 1;
> > -	}
> >  
> > -	memcpy(compound_key + key_field->offset, key, size);
> > +		strncpy(compound_key + key_field->offset, (char *)key, size);
> > +	} else
> > +		memcpy(compound_key + key_field->offset, key, size);
> >  }
> >    
> 
> Shouldn't we use strncpy() in save_comm() too. Feels safer.

Note, if that is changed, it can be another patch. This one is fine as
is. I just was looking at other use cases of memcpy() in that file.

-- Steve