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Date: Mon, 3 Sep 2012 13:41:29 -0300
From: Luiz Capitulino <lcapitulino@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] json-parser: Fix potential NULL pointer
 segfault
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To: Stefan Weil <sw@weilnetz.de>
Cc: qemu-trivial@nongnu.org, Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org

On Sat,  1 Sep 2012 12:52:58 +0200
Stefan Weil <sw@weilnetz.de> wrote:

> Report from smatch:
> json-parser.c:474 parse_object(62) error: potential null derefence 'dict'.
> json-parser.c:553 parse_array(75) error: potential null derefence 'list'.
> 
> Label out can be called with list == NULL.
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
>  json-parser.c |    8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/json-parser.c b/json-parser.c
> index 457291b..c31c759 100644
> --- a/json-parser.c
> +++ b/json-parser.c
> @@ -471,7 +471,9 @@ static QObject *parse_object(JSONParserContext *ctxt, va_list *ap)
>  
>  out:
>      parser_context_restore(ctxt, saved_ctxt);
> -    QDECREF(dict);
> +    if (dict) {
> +        QDECREF(dict);
> +    }

I prefer changing QDECREF() to a nop if obj is NULL.

>      return NULL;
>  }
>  
> @@ -550,7 +552,9 @@ static QObject *parse_array(JSONParserContext *ctxt, va_list *ap)
>  
>  out:
>      parser_context_restore(ctxt, saved_ctxt);
> -    QDECREF(list);
> +    if (list) {
> +        QDECREF(list);
> +    }
>      return NULL;
>  }
>