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Date:   Fri, 17 Jun 2022 17:44:14 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Wang ShaoBo <bobo.shaobowang@huawei.com>
Cc:     <cj.chengjian@huawei.com>, <linux-kernel@vger.kernel.org>,
        <liwei391@huawei.com>, <mhiramat@kernel.org>, <acme@redhat.com>,
        <yuehaibing@huawei.com>
Subject: Re: [PATCH 2/2] libtraceevent: fix free NULL pointer in
 parse_arg_add()
Message-ID: <20220617174414.495392e2@gandalf.local.home>
In-Reply-To: <20220513023308.2400381-3-bobo.shaobowang@huawei.com>
References: <20220513023308.2400381-1-bobo.shaobowang@huawei.com>
        <20220513023308.2400381-3-bobo.shaobowang@huawei.com>
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On Fri, 13 May 2022 10:33:08 +0800
Wang ShaoBo <bobo.shaobowang@huawei.com> wrote:

> Should not call free if parg->format is NULL.
> 
> Fixes: e7a90882b05b ("tools lib traceevent: Optimize pretty_print() function")
> Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
> ---
>  tools/lib/traceevent/event-parse.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
> index 69e4d5229362..b1a07db54457 100644
> --- a/tools/lib/traceevent/event-parse.c
> +++ b/tools/lib/traceevent/event-parse.c
> @@ -5461,9 +5461,11 @@ static int parse_arg_add(struct tep_print_parse **parse, char *format,
>  	return 0;
>  error:
>  	if (parg) {
> -		free(parg->format);
> +		if (parg->format)
> +			free(parg->format);

It's perfectly fine to call free(NULL).

This is not a bug fix.

-- Steve

>  		free(parg);
>  	}
> +
>  	return -1;
>  }
>