FAILED: patch "[PATCH] security/keys: properly zero out sensitive key material in" failed to apply to 4.4-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

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 <stable@xxxxxxxxxxxxxxx>.

thanks,

greg k-h

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

>From 910801809b2e40a4baedd080ef5d80b4a180e70e Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
Date: Wed, 20 Sep 2017 16:58:38 +0200
Subject: [PATCH] security/keys: properly zero out sensitive key material in
 big_key

Error paths forgot to zero out sensitive material, so this patch changes
some kfrees into a kzfrees.

Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-by: Eric Biggers <ebiggers3@xxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Kirill Marinushkin <k.marinushkin@xxxxxxxxx>
Cc: security@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx

diff --git a/security/keys/big_key.c b/security/keys/big_key.c
index 6acb00f6f22c..507d6fb86a4f 100644
--- a/security/keys/big_key.c
+++ b/security/keys/big_key.c
@@ -195,7 +195,7 @@ int big_key_preparse(struct key_preparsed_payload *prep)
 		*path = file->f_path;
 		path_get(path);
 		fput(file);
-		kfree(data);
+		kzfree(data);
 	} else {
 		/* Just store the data in a buffer */
 		void *data = kmalloc(datalen, GFP_KERNEL);
@@ -211,9 +211,9 @@ int big_key_preparse(struct key_preparsed_payload *prep)
 err_fput:
 	fput(file);
 err_enckey:
-	kfree(enckey);
+	kzfree(enckey);
 error:
-	kfree(data);
+	kzfree(data);
 	return ret;
 }
 
@@ -227,7 +227,7 @@ void big_key_free_preparse(struct key_preparsed_payload *prep)
 
 		path_put(path);
 	}
-	kfree(prep->payload.data[big_key_data]);
+	kzfree(prep->payload.data[big_key_data]);
 }
 
 /*
@@ -259,7 +259,7 @@ void big_key_destroy(struct key *key)
 		path->mnt = NULL;
 		path->dentry = NULL;
 	}
-	kfree(key->payload.data[big_key_data]);
+	kzfree(key->payload.data[big_key_data]);
 	key->payload.data[big_key_data] = NULL;
 }
 
@@ -328,7 +328,7 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
 err_fput:
 		fput(file);
 error:
-		kfree(data);
+		kzfree(data);
 	} else {
 		ret = datalen;
 		if (copy_to_user(buffer, key->payload.data[big_key_data],