linux-kernel - [PATCH] ext4: fix big-endian bugs which could cause fs corruptions

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Date:	Wed,  3 Apr 2013 12:36:42 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
	Christian Kujau <lists@...dbynature.de>,
	CAI Qian <caiqian@...hat.com>, sbest@...hat.com,
	Zheng Liu <wenqing.lz@...bao.com>,
	"Theodore Ts'o" <tytso@....edu>,
	Dmitry Monakhov <dmonakhov@...nvz.org>
Subject: [PATCH] ext4: fix big-endian bugs which could cause fs corruptions

From: Zheng Liu <wenqing.lz@...bao.com>

From: Zheng Liu <wenqing.lz@...bao.com>

When an extent was zeroed out, we forgot to do convert from cpu to le16.
It could make us hit a BUG_ON when we try to write dirty pages out.  So
fix it.

[ Also fix a bug found by Dmitry Monakhov where we were missing
  le32_to_cpu() calls in the new indirect punch hole code.

  There are a number of other big endian warnings found by static code
  analyzers, but we'll wait for the next merge window to fix them all
  up.  These fixes are designed to be Obviously Correct by code
  inspection, and easy to demonstrate that it won't make any
  difference (and hence, won't introduce any bugs) on little endian
  architectures such as x86.  --tytso ]

Signed-off-by: Zheng Liu <wenqing.lz@...bao.com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
Reported-by: CAI Qian <caiqian@...hat.com>
Reported-by: Christian Kujau <lists@...dbynature.de>
Cc: Dmitry Monakhov <dmonakhov@...nvz.org>
---

This is what I plan to be sending to Linus very shortly.  If anyone
could  test / review this patch ASAP, I'd really appreciate it, thanks!!

 fs/ext4/extents.c  | 11 +++++++----
 fs/ext4/indirect.c |  4 ++--
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 56efcaa..9c6d06d 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2999,20 +2999,23 @@ static int ext4_split_extent_at(handle_t *handle,
 			if (split_flag & EXT4_EXT_DATA_VALID1) {
 				err = ext4_ext_zeroout(inode, ex2);
 				zero_ex.ee_block = ex2->ee_block;
-				zero_ex.ee_len = ext4_ext_get_actual_len(ex2);
+				zero_ex.ee_len = cpu_to_le16(
+						ext4_ext_get_actual_len(ex2));
 				ext4_ext_store_pblock(&zero_ex,
 						      ext4_ext_pblock(ex2));
 			} else {
 				err = ext4_ext_zeroout(inode, ex);
 				zero_ex.ee_block = ex->ee_block;
-				zero_ex.ee_len = ext4_ext_get_actual_len(ex);
+				zero_ex.ee_len = cpu_to_le16(
+						ext4_ext_get_actual_len(ex));
 				ext4_ext_store_pblock(&zero_ex,
 						      ext4_ext_pblock(ex));
 			}
 		} else {
 			err = ext4_ext_zeroout(inode, &orig_ex);
 			zero_ex.ee_block = orig_ex.ee_block;
-			zero_ex.ee_len = ext4_ext_get_actual_len(&orig_ex);
+			zero_ex.ee_len = cpu_to_le16(
+						ext4_ext_get_actual_len(&orig_ex));
 			ext4_ext_store_pblock(&zero_ex,
 					      ext4_ext_pblock(&orig_ex));
 		}
@@ -3272,7 +3275,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 		if (err)
 			goto out;
 		zero_ex.ee_block = ex->ee_block;
-		zero_ex.ee_len = ext4_ext_get_actual_len(ex);
+		zero_ex.ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex));
 		ext4_ext_store_pblock(&zero_ex, ext4_ext_pblock(ex));
 
 		err = ext4_ext_get_access(handle, inode, path + depth);
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index b505a14..a041831 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -1539,9 +1539,9 @@ static int free_hole_blocks(handle_t *handle, struct inode *inode,
 		blk = *i_data;
 		if (level > 0) {
 			ext4_lblk_t first2;
-			bh = sb_bread(inode->i_sb, blk);
+			bh = sb_bread(inode->i_sb, le32_to_cpu(blk));
 			if (!bh) {
-				EXT4_ERROR_INODE_BLOCK(inode, blk,
+				EXT4_ERROR_INODE_BLOCK(inode, le32_to_cpu(blk),
 						       "Read failure");
 				return -EIO;
 			}
-- 
1.7.12.rc0.22.gcdd159b

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