linux-kernel - Re: [PATCH] jfs: Add missing NULL pointer check in __get

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Message-ID: <1dbf4a54-968f-0ca7-da96-e262c653fecb@canonical.com>
Date:   Wed, 25 Oct 2017 09:50:36 +0200
From:   Juerg Haefliger <juerg.haefliger@...onical.com>
To:     shaggy@...nel.org, jfs-discussion@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] jfs: Add missing NULL pointer check in __get_metapage

Is this a patch you might consider?

Thanks
...Juerg


On 10/04/2017 10:24 AM, Juerg Haefliger wrote:
> alloc_metapage can return a NULL pointer so check for that. And also emit
> an error message if that happens.
> 
> Signed-off-by: Juerg Haefliger <juerg.haefliger@...onical.com>
> ---
>  fs/jfs/jfs_metapage.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
> index 1c4b9ad4d7ab..00f21af66872 100644
> --- a/fs/jfs/jfs_metapage.c
> +++ b/fs/jfs/jfs_metapage.c
> @@ -187,14 +187,18 @@ static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
>  {
>  	struct metapage *mp = mempool_alloc(metapage_mempool, gfp_mask);
>  
> -	if (mp) {
> -		mp->lid = 0;
> -		mp->lsn = 0;
> -		mp->data = NULL;
> -		mp->clsn = 0;
> -		mp->log = NULL;
> -		init_waitqueue_head(&mp->wait);
> +	if (!mp) {
> +		jfs_err("mempool_alloc failed!\n");
> +		return NULL;
>  	}
> +
> +	mp->lid = 0;
> +	mp->lsn = 0;
> +	mp->data = NULL;
> +	mp->clsn = 0;
> +	mp->log = NULL;
> +	init_waitqueue_head(&mp->wait);
> +
>  	return mp;
>  }
>  
> @@ -663,6 +667,8 @@ struct metapage *__get_metapage(struct inode *inode, unsigned long lblock,
>  	} else {
>  		INCREMENT(mpStat.pagealloc);
>  		mp = alloc_metapage(GFP_NOFS);
> +		if (!mp)
> +			goto unlock;
>  		mp->page = page;
>  		mp->sb = inode->i_sb;
>  		mp->flag = 0;
> 



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