linux-kernel - Re: [PATCH] udf: fix an uninitialized read bug

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Date:   Mon, 15 Apr 2019 18:05:17 +0200
From:   Jan Kara <jack@...e.cz>
To:     Wenwen Wang <wang6495@....edu>
Cc:     Jan Kara <jack@...e.com>, open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] udf: fix an uninitialized read bug

On Mon 15-04-19 10:26:24, Wenwen Wang wrote:
> In udf_lookup(), the pointer 'fi' is a local variable initialized by the
> return value of the function call udf_find_entry(). However, if the macro
> 'UDF_RECOVERY' is defined, this variable will become uninitialized if the
> else branch is not taken, which can potentially cause incorrect results in
> the following execution.
> 
> This patch simply initializes this local pointer to NULL.
> 
> Signed-off-by: Wenwen Wang <wang6495@....edu>

Thanks for the patch! A better fix is to drop the whole UDF_RECOVERY ifdef
and what's in it. It is just dead code anyway.

								Honza

> ---
>  fs/udf/namei.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/udf/namei.c b/fs/udf/namei.c
> index 58cc241..9d499e1 100644
> --- a/fs/udf/namei.c
> +++ b/fs/udf/namei.c
> @@ -299,7 +299,7 @@ static struct dentry *udf_lookup(struct inode *dir, struct dentry *dentry,
>  	struct inode *inode = NULL;
>  	struct fileIdentDesc cfi;
>  	struct udf_fileident_bh fibh;
> -	struct fileIdentDesc *fi;
> +	struct fileIdentDesc *fi = NULL;
>  
>  	if (dentry->d_name.len > UDF_NAME_LEN)
>  		return ERR_PTR(-ENAMETOOLONG);
> -- 
> 2.7.4
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR