Patch "ext4: fix use-after-iput when fscrypt contexts are inconsistent" has been added to the 4.9-stable tree

Patch "ext4: fix use-after-iput when fscrypt contexts are inconsistent" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ext4: fix use-after-iput when fscrypt contexts are inconsistent

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ext4-fix-use-after-iput-when-fscrypt-contexts-are-inconsistent.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From dd01b690f8f4b1e414f89e5a9a5326bf720d6652 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Wed, 1 Feb 2017 21:07:11 -0500
Subject: ext4: fix use-after-iput when fscrypt contexts are inconsistent

From: Eric Biggers <ebiggers@google.com>

commit dd01b690f8f4b1e414f89e5a9a5326bf720d6652 upstream.

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.

Fixes: d9cdc9033181 ("ext4 crypto: enforce context consistency")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ext4/namei.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1616,13 +1616,15 @@ static struct dentry *ext4_lookup(struct
 		    !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);
 		}
 	}


Patches currently in stable-queue which might be from ebiggers@google.com are

queue-4.9/ext4-fix-use-after-iput-when-fscrypt-contexts-are-inconsistent.patch