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

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Message-ID: <20171009182432.7c2e0d04@gandalf.local.home>
Date:   Mon, 9 Oct 2017 18:24:32 -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 Sat, 12 Aug 2017 11:30:44 -0600
Michael Sartain <mikesart@...tmail.com> wrote:

> Signed-off-by: Michael Sartain <mikesart@...tmail.com>
> ---
>  trace-output.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/trace-output.c b/trace-output.c
> index bfe6331..84b21b0 100644
> --- a/trace-output.c
> +++ b/trace-output.c
> @@ -929,7 +929,11 @@ tracecmd_add_option(struct tracecmd_output *handle,
>  		free(option);
>  		return NULL;
>  	}
> -	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?

-- Steve

> +
>  	list_add_tail(&option->list, &handle->options);
>  
>  	return option;