[PATCH] ext4: Check for encryption feature before fscrypt_process_policy()

...otherwise an user can enable encryption for certain files even
when the filesystem is unable to support it.
Such a case would be a filesystem created by mkfs.ext4's default
settings, 1KiB block size. Ext4 supports encyption only when block size
is equal to PAGE_SIZE.
But this constraint is only checked when the encryption feature flag
is set.

Signed-off-by: Richard Weinberger <richard@nod.at>
---
 fs/ext4/ioctl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 1bb7df5..9e9a73e 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c

@@ -772,6 +772,9 @@ resizefs_out:
 #ifdef CONFIG_EXT4_FS_ENCRYPTION
 		struct fscrypt_policy policy;
 
+		if (!ext4_has_feature_encrypt(sb))
+			return -EOPNOTSUPP;
+
 		if (copy_from_user(&policy,
 				   (struct fscrypt_policy __user *)arg,
 				   sizeof(policy)))

-- 
2.7.3