linux-kernel - Re: [PATCH v2] ocfs2: quota_local: fix possible uninitialized-variable access in ocfs2_local_read

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Date:   Wed, 4 Aug 2021 10:36:59 +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>
Subject: Re: [PATCH v2] ocfs2: quota_local: fix possible
 uninitialized-variable access in ocfs2_local_read_info()



On 8/4/21 9:45 AM, Tuo Li wrote:
> A memory block is allocated through kmalloc(), and its return value is
> assigned to the pointer oinfo. If the return value of
> ocfs2_global_read_info() at line 709 is less than zero,
> oinfo->dqi_gqinode may be not initialized. However, it is accessed at
> line 775:
>   iput(oinfo->dqi_gqinode);
> 
> To fix this possible uninitialized-variable access, replace kmalloc()
> with kzalloc() when allocating memory for oinfo.
> 

Update description as well.

> Reported-by: TOTE Robot <oslab@...nghua.edu.cn>
> Signed-off-by: Tuo Li <islituo@...il.com>
> ---
> v2:
> * Replace kzalloc() with NULL assignment to oinfo->dqi_gqinode.
>   Thank Joseph Qi for helpful advice.
> ---
>  fs/ocfs2/quota_local.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
> index b1a8b046f4c2..de5aae584d5d 100644
> --- a/fs/ocfs2/quota_local.c
> +++ b/fs/ocfs2/quota_local.c
> @@ -703,6 +703,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
>  	oinfo->dqi_type = type;
>  	INIT_LIST_HEAD(&oinfo->dqi_chunk);
>  	oinfo->dqi_rec = NULL;
> +	oinfo->dqi_gqinode = NULL;
>  	oinfo->dqi_lqi_bh = NULL;
>  	oinfo->dqi_libh = NULL;
>  

We need take care oinfo->dqi_gqlock as well. How about the following way?

diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index eda8348..f033de7 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 b1a8b04..0e4b16d 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;