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

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>

1 files changed, 3 insertions, 5 deletions

diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 734abca25e35..fe64d9f79852 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -481,7 +481,7 @@ 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,
@@ -489,8 +489,7 @@ 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));
         /*
@@ -618,8 +617,7 @@ err_out:
 
         ext4_journal_stop(handle);
 
-        if (tmp_inode)
-                iput(tmp_inode);
+        iput(tmp_inode);
 
         return retval;
 }