linux-kernel - Re: [PATCH v3] ocfs2: quota_local: fix possible uninitialized-variable access in ocfs2_local_read

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Message-ID: <d19dd958-93f6-bc42-b419-c60571de9b70@linux.alibaba.com>
Date:   Wed, 4 Aug 2021 11:26:50 +0800
From:   Joseph Qi <joseph.qi@...ux.alibaba.com>
To:     Tuo Li <islituo@...il.com>, mark@...heh.com, jlbec@...lplan.org
Cc:     ocfs2-devel@....oracle.com, linux-kernel@...r.kernel.org,
        baijiaju1990@...il.com, TOTE Robot <oslab@...nghua.edu.cn>,
        akpm <akpm@...ux-foundation.org>
Subject: Re: [PATCH v3] ocfs2: quota_local: fix possible
 uninitialized-variable access in ocfs2_local_read_info()



On 8/4/21 11:18 AM, Tuo Li wrote:
> A memory block is allocated through kmalloc(), and its return value is
> assigned to the pointer oinfo. However, oinfo->dqi_gqinode is not
> initialized but it is accessed in:
>   iput(oinfo->dqi_gqinode);
> 
> To fix this possible uninitialized-variable access, assign NULL to
> oinfo->dqi_gqinode, and add ocfs2_qinfo_lock_res_init()
> behind the assignment in ocfs2_local_read_info(). Remove
> ocfs2_qinfo_lock_res_init() in ocfs2_global_read_info().
> 

Or we can simplify the above description to:
"To fix the possible uninitialized-variable access, initialize
dqi_gqinode and dqi_gqlock first before calling
ocfs2_global_read_info()."

> Reported-by: TOTE Robot <oslab@...nghua.edu.cn>
> Signed-off-by: Tuo Li <islituo@...il.com>

Reviewed-by: Joseph Qi <joseph.qi@...ux.alibaba.com>
> ---
> v3:
> * Update description.
> * Assign NULL to oinfo->dqi_gqinode, and add ocfs2_qinfo_lock_res_init()
> behind the assignment in ocfs2_local_read_info(). Remove
> ocfs2_qinfo_lock_res_init() in ocfs2_global_read_info()
>   Thank Joseph Qi for helpful advice.
> v2:
> * Replace kzalloc() with NULL assignment to oinfo->dqi_gqinode.
>   Thank Joseph Qi for helpful advice.
> ---
>  fs/ocfs2/quota_global.c | 1 -
>  fs/ocfs2/quota_local.c  | 2 ++
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
> index eda83487c9ec..f033de733adb 100644
> --- a/fs/ocfs2/quota_global.c
> +++ b/fs/ocfs2/quota_global.c
> @@ -357,7 +357,6 @@ int ocfs2_global_read_info(struct super_block *sb, int type)
>  	}
>  	oinfo->dqi_gi.dqi_sb = sb;
>  	oinfo->dqi_gi.dqi_type = type;
> -	ocfs2_qinfo_lock_res_init(&oinfo->dqi_gqlock, oinfo);
>  	oinfo->dqi_gi.dqi_entry_size = sizeof(struct ocfs2_global_disk_dqblk);
>  	oinfo->dqi_gi.dqi_ops = &ocfs2_global_ops;
>  	oinfo->dqi_gqi_bh = NULL;
> diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
> index b1a8b046f4c2..0e4b16d4c037 100644
> --- a/fs/ocfs2/quota_local.c
> +++ b/fs/ocfs2/quota_local.c
> @@ -702,6 +702,8 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
>  	info->dqi_priv = oinfo;
>  	oinfo->dqi_type = type;
>  	INIT_LIST_HEAD(&oinfo->dqi_chunk);
> +	oinfo->dqi_gqinode = NULL;
> +	ocfs2_qinfo_lock_res_init(&oinfo->dqi_gqlock, oinfo);
>  	oinfo->dqi_rec = NULL;
>  	oinfo->dqi_lqi_bh = NULL;
>  	oinfo->dqi_libh = NULL;
>