ext4: Fix NULL dereference in ext4_ext_migrate()'s error handling

(cherry picked from commit 090542641de833c6f756895fc2f139f046e298f9)

This was found through a code checker (http://repo.or.cz/w/smatch.git/).
It looks like you might be able to trigger the error by trying to migrate
a readonly file system.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index f2a9cf498ecda12ddde2c7fb1a73a40c64767ade..9aa0fbee8aa8e43d0201a5f8f2584c32965ec978 100644 (file)
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -480,7 +480,7 @@ int ext4_ext_migrate(struct inode *inode)
                                        + 1);
        if (IS_ERR(handle)) {
                retval = PTR_ERR(handle);
-               goto err_out;
+               return retval;
        }
        tmp_inode = ext4_new_inode(handle,
                                inode->i_sb->s_root->d_inode,
@@ -488,8 +488,7 @@ int ext4_ext_migrate(struct inode *inode)
        if (IS_ERR(tmp_inode)) {
                retval = -ENOMEM;
                ext4_journal_stop(handle);
-               tmp_inode = NULL;
-               goto err_out;
+               return retval;
        }
        i_size_write(tmp_inode, i_size_read(inode));
        /*
@@ -617,8 +616,7 @@ err_out:
 
        ext4_journal_stop(handle);
 
-       if (tmp_inode)
-               iput(tmp_inode);
+       iput(tmp_inode);
 
        return retval;
 }