linux-ext4 - [PATCH 2/3] ext4: Fix the NULL reference in double_down_write_data

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Date:	Wed, 03 Mar 2010 15:49:37 +0900
From:	Akira Fujita <a-fujita@...jp.nec.com>
To:	Theodore Tso <tytso@....edu>
CC:	ext4 development <linux-ext4@...r.kernel.org>
Subject: [PATCH 2/3] ext4: Fix the NULL reference in double_down_write_data_sem()

ext4: Fix the NULL reference in double_down_write_data_sem()

From: Akira Fujita <a-fujita@...jp.nec.com>

If EXT4_IOC_MOVE_EXT ioctl is called with NULL donor_fd,
fget() in ext4_ioctl() gets inappropriate file structure for donor.
Therefore the NULL reference occurs in double_down_write_data_sem().

Signed-off-by: Akira Fujita <a-fujita@...jp.nec.com>
---
  fs/ext4/move_extent.c |   16 ++++++++--------
  1 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 9eca1c0..7e99f4e 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -953,14 +953,6 @@ mext_check_arguments(struct inode *orig_inode,
  	unsigned int blkbits = orig_inode->i_blkbits;
  	unsigned int blocksize = 1 << blkbits;

-	/* Regular file check */
-	if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
-		ext4_debug("ext4 move extent: The argument files should be "
-			"regular file [ino:orig %lu, donor %lu]\n",
-			orig_inode->i_ino, donor_inode->i_ino);
-		return -EINVAL;
-	}
-
  	if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
  		ext4_debug("ext4 move extent: suid or sgid is set"
  			   " to donor file [ino:orig %lu, donor %lu]\n",
@@ -1208,6 +1200,14 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
  		return -EINVAL;
  	}

+	/* Regular file check */
+	if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
+		ext4_debug("ext4 move extent: The argument files should be "
+			"regular file [ino:orig %lu, donor %lu]\n",
+			orig_inode->i_ino, donor_inode->i_ino);
+		return -EINVAL;
+	}
+
  	/* Protect orig and donor inodes against a truncate */
  	ret1 = mext_inode_double_lock(orig_inode, donor_inode);
  	if (ret1 < 0)
--
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