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

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Message-Id: <B8173E0E-2FBC-4EAF-97EF-BF816CEBA26A@dilger.ca>
Date:   Mon, 12 Mar 2018 12:18:11 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Ext4 Developers List <linux-ext4@...r.kernel.org>,
        lczerner@...hat.com
Subject: Re: [PATCH] e2fsck: fix endianness problem when reading htree nodes

On Mar 10, 2018, at 3:47 PM, Theodore Ts'o <tytso@....edu> 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.
> 
> 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>

Looks good.

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

> ---
> 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
> 


Cheers, Andreas






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