linux-kernel - Re: [f2fs-dev] [PATCH 1/3] f2fs: check filename length in recover

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Message-id: <1387761931.2101.289.camel@kjgkr>
Date:	Mon, 23 Dec 2013 10:25:31 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Chao Yu <chao2.yu@...sung.com>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 1/3] f2fs: check filename length in
 recover_dentry

2013-12-21 (토), 18:01 +0800, Chao Yu:
> In current flow, we will get Null return value of f2fs_find_entry in
> recover_dentry when name.len is bigger than F2FS_NAME_LEN, and then we
> still add this inode into its dir entry.
> To avoid this situation, we must check filename length before we use it.
> 
> Another point is that we could remove the code of checking filename length
> In f2fs_find_entry, because f2fs_lookup will be called previously to ensure of
> validity of filename length.
> 
> Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> ---
>  fs/f2fs/dir.c      |    3 ---
>  fs/f2fs/recovery.c |    5 +++++
>  2 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index 0cc26ba..3f3b661 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -190,9 +190,6 @@ struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
>  	unsigned int max_depth;
>  	unsigned int level;
>  
> -	if (unlikely(namelen > F2FS_NAME_LEN))
> -		return NULL;
> -
>  	if (npages == 0)
>  		return NULL;
>  
> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> index a3f4542..fdd175b 100644
> --- a/fs/f2fs/recovery.c
> +++ b/fs/f2fs/recovery.c
> @@ -62,6 +62,11 @@ static int recover_dentry(struct page *ipage, struct inode *inode)
>  
>  	name.len = le32_to_cpu(raw_inode->i_namelen);
>  	name.name = raw_inode->i_name;
> +
> +	if (unlikely(name.len > F2FS_NAME_LEN)) {
> +		err = -ENAMETOOLONG;
> +		goto out;
> +	}

Have you seen this before?
This is a trivial bug case, so, if you have got this bug, we should fix
the bug first instead of adding any workaround patch.
Let's add WARN_ON() at least.
Thanks,

>  retry:
>  	de = f2fs_find_entry(dir, &name, &page);
>  	if (de && inode->i_ino == le32_to_cpu(de->ino))

-- 
Jaegeuk Kim
Samsung

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