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Date:   Tue, 14 May 2019 09:32:10 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Chengguang Xu <cgxu519@...o.com.cn>
Cc:     Jan Kara <jack@...e.com>, linux-ext4 <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] ext2: introduce helper for xattr header validation

On May 13, 2019, at 4:40 PM, Chengguang Xu <cgxu519@...o.com.cn> wrote:
> 
> Introduce helper function ext2_xattr_header_valid()
> for xattr header validation and clean up the header
> check ralated code.
> 
> Signed-off-by: Chengguang Xu <cgxu519@...o.com.cn>

Reviewed-by: Andreas Dilger <adilger@...ger.ca>

> ---
> v1->v2:
> - Pass xattr header to ext2_xattr_header_valid().
> - Change signed-off mail address.
> 
> fs/ext2/xattr.c | 31 ++++++++++++++++++++-----------
> 1 file changed, 20 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
> index 1e33e0ac8cf1..db27260d6a5b 100644
> --- a/fs/ext2/xattr.c
> +++ b/fs/ext2/xattr.c
> @@ -134,6 +134,16 @@ ext2_xattr_handler(int name_index)
> 	return handler;
> }
> 
> +static bool
> +ext2_xattr_header_valid(struct ext2_xattr_header *header)
> +{
> +	if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
> +	    header->h_blocks != cpu_to_le32(1))
> +		return false;
> +
> +	return true;
> +}
> +
> /*
>  * ext2_xattr_get()
>  *
> @@ -176,9 +186,9 @@ ext2_xattr_get(struct inode *inode, int name_index, const char *name,
> 	ea_bdebug(bh, "b_count=%d, refcount=%d",
> 		atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
> 	end = bh->b_data + bh->b_size;
> -	if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
> -	    HDR(bh)->h_blocks != cpu_to_le32(1)) {
> -bad_block:	ext2_error(inode->i_sb, "ext2_xattr_get",
> +	if (!ext2_xattr_header_valid(HDR(bh))) {
> +bad_block:
> +		ext2_error(inode->i_sb, "ext2_xattr_get",
> 			"inode %ld: bad block %d", inode->i_ino,
> 			EXT2_I(inode)->i_file_acl);
> 		error = -EIO;
> @@ -266,9 +276,9 @@ ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
> 	ea_bdebug(bh, "b_count=%d, refcount=%d",
> 		atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount));
> 	end = bh->b_data + bh->b_size;
> -	if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
> -	    HDR(bh)->h_blocks != cpu_to_le32(1)) {
> -bad_block:	ext2_error(inode->i_sb, "ext2_xattr_list",
> +	if (!ext2_xattr_header_valid(HDR(bh))) {
> +bad_block:
> +		ext2_error(inode->i_sb, "ext2_xattr_list",
> 			"inode %ld: bad block %d", inode->i_ino,
> 			EXT2_I(inode)->i_file_acl);
> 		error = -EIO;
> @@ -406,9 +416,9 @@ ext2_xattr_set(struct inode *inode, int name_index, const char *name,
> 			le32_to_cpu(HDR(bh)->h_refcount));
> 		header = HDR(bh);
> 		end = bh->b_data + bh->b_size;
> -		if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
> -		    header->h_blocks != cpu_to_le32(1)) {
> -bad_block:		ext2_error(sb, "ext2_xattr_set",
> +		if (!ext2_xattr_header_valid(header)) {
> +bad_block:
> +			ext2_error(sb, "ext2_xattr_set",
> 				"inode %ld: bad block %d", inode->i_ino,
> 				   EXT2_I(inode)->i_file_acl);
> 			error = -EIO;
> @@ -784,8 +794,7 @@ ext2_xattr_delete_inode(struct inode *inode)
> 		goto cleanup;
> 	}
> 	ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count)));
> -	if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) ||
> -	    HDR(bh)->h_blocks != cpu_to_le32(1)) {
> +	if (!ext2_xattr_header_valid(HDR(bh))) {
> 		ext2_error(inode->i_sb, "ext2_xattr_delete_inode",
> 			"inode %ld: bad block %d", inode->i_ino,
> 			EXT2_I(inode)->i_file_acl);
> --
> 2.17.2
> 
> 


Cheers, Andreas






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