[102/165] ext4: Fix the NULL reference in double_down_write_data_sem()

[Greg KH <gregkh@suse.de>]

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

commit 7247c0caa23d94a1cb6b307edba9dc45fb0798d4 upstream (as of v2.6.33-git11)

If EXT4_IOC_MOVE_EXT ioctl is called with NULL donor_fd, fget() in
ext4_ioctl() gets inappropriate file structure for donor; so we need
to do this check earlier, before calling double_down_write_data_sem().

Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 fs/ext4/move_extent.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -953,14 +953,6 @@ mext_check_arguments(struct inode *orig_
 	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",
@@ -1207,6 +1199,14 @@ ext4_move_extents(struct file *o_filp, s
 			orig_inode->i_ino, donor_inode->i_ino);
 		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);