FAILED: patch "[PATCH] ext4: fix use-after-iput when fscrypt contexts are" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Eric Biggers <[email protected]>
Date: Wed, 1 Feb 2017 21:07:11 -0500
Subject: [PATCH] ext4: fix use-after-iput when fscrypt contexts are
inconsistent

In the case where the child's encryption context was inconsistent with its parent directory, we were using inode->i_sb and inode->i_ino after the inode had already been iput(). Fix this by doing the iput() in the correct places.

Note: only ext4 had this bug, not f2fs and ubifs.

index bb880c326191..931da9d5d915 100644
@@ -1618,13 +1618,15 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
 		    !fscrypt_has_permitted_context(dir, inode)) {
 			int nokey = ext4_encrypted_inode(inode) &&
 				!fscrypt_has_encryption_key(inode);
-			iput(inode);
-			if (nokey)
+			if (nokey) {
+				iput(inode);
 				return ERR_PTR(-ENOKEY);
+			}
 			ext4_warning(inode->i_sb,
 				     "Inconsistent encryption contexts: %lu/%lu",
 				     (unsigned long) dir->i_ino,
 				     (unsigned long) inode->i_ino);
+			iput(inode);
 			return ERR_PTR(-EPERM);
 		}
 	}