linux-ext4 - Re: [PATCH] e2fsck: fix endianness problem when reading htree nodes

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Date:   Mon, 12 Mar 2018 06:43:48 +0100
From:   Lukas Czerner <lczerner@...hat.com>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Ext4 Developers List <linux-ext4@...r.kernel.org>,
        adilger@...ger.ca
Subject: Re: [PATCH] e2fsck: fix endianness problem when reading htree nodes

On Sat, Mar 10, 2018 at 05:47:33PM -0500, Theodore Ts'o wrote:
> From: Lukas Czerner <lczerner@...hat.com>
> 
> Wrong directory block number can be saved in ->previous on big endian
> system in parse_int_node(). Fix it by moving the mask out of the endian
> conversion.

Thanks for the fix-up Ted. It looks good.

-Lukas

> 
> Fixes: ae9efd05a986 ("e2fsck: 3 level hash tree directory optimization")
> Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> Signed-off-by: Theodore Ts'o <tytso@....edu>
> ---
>  e2fsck/pass2.c       | 5 +++--
>  lib/ext2fs/ext2_fs.h | 2 ++
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/e2fsck/pass2.c b/e2fsck/pass2.c
> index 1b0504c85..e922876d3 100644
> --- a/e2fsck/pass2.c
> +++ b/e2fsck/pass2.c
> @@ -643,7 +643,7 @@ static void parse_int_node(ext2_filsys fs,
>  		printf("Entry #%d: Hash 0x%08x, block %u\n", i,
>  		       hash, ext2fs_le32_to_cpu(ent[i].block));
>  #endif
> -		blk = ext2fs_le32_to_cpu(ent[i].block) & 0x0ffffff;
> +		blk = ext2fs_le32_to_cpu(ent[i].block) & EXT4_DX_BLOCK_MASK;
>  		/* Check to make sure the block is valid */
>  		if (blk >= (blk_t) dx_dir->numblocks) {
>  			cd->pctx.blk = blk;
> @@ -664,7 +664,8 @@ static void parse_int_node(ext2_filsys fs,
>  		}
>  
>  		dx_db->previous =
> -			i ? ext2fs_le32_to_cpu(ent[i-1].block & 0x0ffffff) : 0;
> +			i ? (ext2fs_le32_to_cpu(ent[i-1].block) &
> +			     EXT4_DX_BLOCK_MASK) : 0;
>  
>  		if (hash < min_hash)
>  			min_hash = hash;
> diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
> index 2496d16da..7d6269413 100644
> --- a/lib/ext2fs/ext2_fs.h
> +++ b/lib/ext2fs/ext2_fs.h
> @@ -232,6 +232,8 @@ struct ext2_dx_root_info {
>  
>  #define EXT2_HASH_FLAG_INCOMPAT	0x1
>  
> +#define EXT4_DX_BLOCK_MASK 0x0fffffff
> +
>  struct ext2_dx_entry {
>  	__le32 hash;
>  	__le32 block;
> -- 
> 2.16.1.72.g5be1f00a9a
>