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

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Message-Id: <20180310224733.29843-1-tytso@mit.edu>
Date:   Sat, 10 Mar 2018 17:47:33 -0500
From:   Theodore Ts'o <tytso@....edu>
To:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:     adilger@...ger.ca, lczerner@...hat.com,
        Theodore Ts'o <tytso@....edu>
Subject: [PATCH] e2fsck: fix endianness problem when reading htree nodes

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>
---
 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