Re: [PATCH 2/3] libxl/remus: Move the assert before the info is used.

From: Ian Campbell <ian.campbell@citrix.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	xen-devel@lists.xenproject.org, wei.liu2@citrix.com,
	ian.jackson@eu.citrix.com
Cc: Wen Congyang <wency@cn.fujitsu.com>,
	Yang Hongyang <hongyang.yang@easystack.cn>
Subject: Re: [PATCH 2/3] libxl/remus: Move the assert before the info is used.
Date: Tue, 26 Jan 2016 16:21:28 +0000	[thread overview]
Message-ID: <1453825288.25257.32.camel@citrix.com> (raw)
In-Reply-To: <1453756017-8747-3-git-send-email-konrad.wilk@oracle.com>

On Mon, 2016-01-25 at 16:06 -0500, Konrad Rzeszutek Wilk wrote:
> The assert(info) is after quite a lot of manipulations
> on 'info' - which makes the assert pointless because if
> info was NULL it would have crashed earlier.
> 
> Move it earlier so that it guards before we try using
> the 'info' structure.

That assert (wherever it is placed) is rather aggressive for an application
provided argument. ERROR_INVALID would be more normal I think.

> 
> CC: Wen Congyang <wency@cn.fujitsu.com>
> CC: Yang Hongyang <hongyang.yang@easystack.cn>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
>  tools/libxl/libxl.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 2bde0f5..60974cc 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -855,6 +855,8 @@ int libxl_domain_remus_start(libxl_ctx *ctx,
> libxl_domain_remus_info *info,
>          goto out;
>      }
>  
> +    assert(info);
> +
>      libxl_defbool_setdefault(&info->allow_unsafe, false);
>      libxl_defbool_setdefault(&info->blackhole, false);
>      libxl_defbool_setdefault(&info->compression, true);
> @@ -883,8 +885,6 @@ int libxl_domain_remus_start(libxl_ctx *ctx,
> libxl_domain_remus_info *info,
>      dss->debug = 0;
>      dss->remus = info;
>  
> -    assert(info);
> -
>      /* Point of no return */
>      libxl__remus_setup(egc, dss);
>      return AO_INPROGRESS;

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