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

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Date:   Sat, 31 Jul 2021 21:57:13 +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] ocfs2: quota_local: fix possible uninitialized-variable
 access in ocfs2_local_read_info()

Thanks for the efforts.
For the issue you mentioned, I'd like just initialized
oinfo->dqi_gqinode as NULL before calling ocfs2_global_read_info().
But it seems still have other issues here such as dqi_gqlock.
We need take care all those initialized in ocfs2_global_read_info()
carefully.

Thanks,
Joseph

On 7/31/21 3:56 PM, 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.
> 
> Reported-by: TOTE Robot <oslab@...nghua.edu.cn>
> Signed-off-by: Tuo Li <islituo@...il.com>
> ---
>  fs/ocfs2/quota_local.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
> index b1a8b046f4c2..4c1219e08b49 100644
> --- a/fs/ocfs2/quota_local.c
> +++ b/fs/ocfs2/quota_local.c
> @@ -693,7 +693,7 @@ static int ocfs2_local_read_info(struct super_block *sb, int type)
>  
>  	info->dqi_max_spc_limit = 0x7fffffffffffffffLL;
>  	info->dqi_max_ino_limit = 0x7fffffffffffffffLL;
> -	oinfo = kmalloc(sizeof(struct ocfs2_mem_dqinfo), GFP_NOFS);
> +	oinfo = kzalloc(sizeof(struct ocfs2_mem_dqinfo), GFP_NOFS);
>  	if (!oinfo) {
>  		mlog(ML_ERROR, "failed to allocate memory for ocfs2 quota"
>  			       " info.");
>