linux-kernel - Re: [PATCH] mvsas:Fix possible NULL pointer deference in mvs_dev_found

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Message-ID: <5777A288.90608@osg.samsung.com>
Date:	Sat, 02 Jul 2016 12:16:24 +0100
From:	Luis de Bethencourt <luisbg@....samsung.com>
To:	Nicholas Krause <xerofoify@...il.com>, jejb@...ux.vnet.ibm.com
CC:	martin.petersen@...cle.com, jthumshirn@...e.de, tj@...nel.org,
	James.Bottomley@...senPartnership.com, Wilfried.Weissmann@....at,
	davispuh@...il.com, linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mvsas:Fix possible NULL pointer deference in mvs_dev_found_notify

On 01/07/16 18:43, Nicholas Krause wrote:
> This adds properly checking after the call to mvs_find_dev_mvi
> due to this function being able to return a NULL pointer and if
> this does arise we will deference it in mvs_alloc_dev due to
> this function never checking if a NULL pointer is given as
> it's input argument.
> v2 - Fix NULL pointer deferenece in error path by calling
> spin_unlock_irqrestore on the now NULL pointer, as returned
> by mvs_find_dev_mvi.

Hi Nicholas,

You mention v2 here but this is [PATCH] and not [PATCH v2]. Is this
the first version of the patch or second?

> 
> Signed-off-by: Nicholas Krause <xerofoify@...il.com>
> ---

If the "v2 -" comments are part of the review and not of the git commit
message it is better to place it here. Between the "---" and the diff.

This is because when the maintainer applies the patch this section will
be truncated, and it won't show in the git log.

>  drivers/scsi/mvsas/mv_sas.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/scsi/mvsas/mv_sas.c b/drivers/scsi/mvsas/mv_sas.c
> index 83cd3ea..74f3954 100644
> --- a/drivers/scsi/mvsas/mv_sas.c
> +++ b/drivers/scsi/mvsas/mv_sas.c
> @@ -1191,6 +1191,10 @@ int mvs_dev_found_notify(struct domain_device *dev, int lock)
>  	struct mvs_device *mvi_device;
>  
>  	mvi = mvs_find_dev_mvi(dev);
> +	if (!mvi) {
> +		res = -1;
> +		goto found_null;
> +	}
>  
>  	if (lock)
>  		spin_lock_irqsave(&mvi->lock, flags);
> @@ -1230,6 +1234,7 @@ int mvs_dev_found_notify(struct domain_device *dev, int lock)
>  found_out:
>  	if (lock)
>  		spin_unlock_irqrestore(&mvi->lock, flags);
> +found_null:
>  	return res;
>  }
>  
> 

If the goto is just going to return, why not do a return directly instead?

if (!mvi)
    return -1;

Thanks for the patch,
Luis