Patch "fscrypto: require write access to mount to set encryption policy" has been added to the 4.4-stable tree

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

fscrypto: require write access to mount to set encryption policy

to the 4.4-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:
fscrypto-require-write-access-to-mount-to-set-encryption-policy.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Eric Biggers <[email protected]>
Date: Thu, 8 Sep 2016 14:20:38 -0700
Subject: fscrypto: require write access to mount to set encryption policy

From: Eric Biggers <[email protected]>

commit ba63f23d69a3a10e7e527a02702023da68ef8a6d upstream.

Since setting an encryption policy requires writing metadata to the filesystem, it should be guarded by mnt_want_write/mnt_drop_write. Otherwise, a user could cause a write to a frozen or readonly filesystem. This was handled correctly by f2fs but not by ext4. Make fscrypt_process_policy() handle it rather than relying on the filesystem to get it right.

---
 fs/ext4/ioctl.c |    6 ++++++
 1 file changed, 6 insertions(+)

@@ -629,7 +629,13 @@ resizefs_out:
 			goto encryption_policy_out;
 		}
 
+		err = mnt_want_write_file(filp);
+		if (err)
+			goto encryption_policy_out;
+
 		err = ext4_process_policy(&policy, inode);
+
+		mnt_drop_write_file(filp);
 encryption_policy_out:
 		return err;
 #else

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/fscrypto-require-write-access-to-mount-to-set-encryption-policy.patch queue-4.4/fscrypto-add-authorization-check-for-setting-encryption-policy.patch