linux-kernel - Re: [PATCH] mtip32xx: Uninitialized variable in mtip_no_dev

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Message-ID: <0bb97411-d1bd-5c6c-69d0-a7bceb69efa7@fb.com>
Date:   Fri, 21 Apr 2017 13:39:54 -0600
From:   Jens Axboe <axboe@...com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Christoph Hellwig <hch@....de>
CC:     Johannes Thumshirn <jthumshirn@...e.de>,
        Hannes Reinecke <hare@...e.com>,
        Bart Van Assche <Bart.VanAssche@...disk.com>,
        Sachin Shukla <sachin.s5@...sung.com>,
        Pan Bian <bianpan2016@....com>,
        Ming Lei <tom.leiming@...il.com>,
        Eric Biggers <ebiggers@...gle.com>,
        Mike Christie <mchristi@...hat.com>,
        Dan Williams <dan.j.williams@...el.com>,
        <linux-kernel@...r.kernel.org>, <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] mtip32xx: Uninitialized variable in mtip_no_dev_cleanup()

On 04/21/2017 01:37 PM, Dan Carpenter wrote:
> We set "cmd->state = -ENODEV;" but "cmd" hasn't been initialized yet.
> It's weird that GCC doesn't catch this.

That is weird...

> diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
> index 66a6bd83faae..bd4bf70a5bcd 100644
> --- a/drivers/block/mtip32xx/mtip32xx.c
> +++ b/drivers/block/mtip32xx/mtip32xx.c
> @@ -4105,14 +4105,12 @@ static int mtip_block_initialize(struct driver_data *dd)
>  static void mtip_no_dev_cleanup(struct request *rq, void *data, bool reserv)
>  {
>  	struct driver_data *dd = (struct driver_data *)data;
> -	struct mtip_cmd *cmd;
> +	struct mtip_cmd *cmd = mtip_cmd_from_tag(dd, MTIP_TAG_INTERNAL);
>  
>  	if (likely(!reserv)) {
>  		cmd->status = -ENODEV;
>  		blk_mq_complete_request(rq);
>  	} else if (test_bit(MTIP_PF_IC_ACTIVE_BIT, &dd->port->flags)) {
> -
> -		cmd = mtip_cmd_from_tag(dd, MTIP_TAG_INTERNAL);
>  		if (cmd->comp_func)
>  			cmd->comp_func(dd->port, MTIP_TAG_INTERNAL,
>  					cmd, -ENODEV);

This is wrong, you can't use the internal tag bit for both cases. A proper
fix was already merged earlier today:

http://git.kernel.dk/cgit/linux-block/commit/?h=for-4.12/block&id=95c55ff425faa190fd8ba55090fbdf33d8b2f0ae

-- 
Jens Axboe