Patch "KEYS: reject NULL restriction string when type is specified" has been added to the 4.14-stable tree

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

KEYS: reject NULL restriction string when type is specified

to the 4.14-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:
keys-reject-null-restriction-string-when-type-is-specified.patch
and it can be found in the queue-4.14 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: Fri, 8 Dec 2017 15:13:29 +0000
Subject: KEYS: reject NULL restriction string when type is specified

From: Eric Biggers <[email protected]>

commit 18026d866801d0c52e5550210563222bd6c7191d upstream.

keyctl_restrict_keyring() allows through a NULL restriction when the "type" is non-NULL, which causes a NULL pointer dereference in asymmetric_lookup_restriction() when it calls strcmp() on the restriction string.

But no key types actually use a "NULL restriction" to mean anything, so update keyctl_restrict_keyring() to reject it with EINVAL.

---
 security/keys/keyctl.c |   24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

@@ -1588,9 +1588,8 @@ error_keyring:
  * The caller must have Setattr permission to change keyring restrictions.
  *
  * The requested type name may be a NULL pointer to reject all attempts
- * to link to the keyring. If _type is non-NULL, _restriction can be
- * NULL or a pointer to a string describing the restriction. If _type is
- * NULL, _restriction must also be NULL.
+ * to link to the keyring.  In this case, _restriction must also be NULL.
+ * Otherwise, both _type and _restriction must be non-NULL.
  *
  * Returns 0 if successful.
  */

@@ -1598,7 +1597,6 @@ long keyctl_restrict_keyring(key_serial_
 			     const char __user *_restriction)
 {
 	key_ref_t key_ref;
-	bool link_reject = !_type;
 	char type[32];
 	char *restriction = NULL;
 	long ret;

@@ -1607,31 +1605,29 @@ long keyctl_restrict_keyring(key_serial_
 	if (IS_ERR(key_ref))
 		return PTR_ERR(key_ref);
 
+	ret = -EINVAL;
 	if (_type) {
+		if (!_restriction)
+			goto error;
+
 		ret = key_get_type_from_user(type, _type, sizeof(type));
 		if (ret < 0)
 			goto error;
-	}
-
-	if (_restriction) {
-		if (!_type) {
-			ret = -EINVAL;
-			goto error;
-		}
 
 		restriction = strndup_user(_restriction, PAGE_SIZE);
 		if (IS_ERR(restriction)) {
 			ret = PTR_ERR(restriction);
 			goto error;
 		}
+	} else {
+		if (_restriction)
+			goto error;
 	}
 
-	ret = keyring_restrict(key_ref, link_reject ? NULL : type, restriction);
+	ret = keyring_restrict(key_ref, _type ? type : NULL, restriction);
 	kfree(restriction);
-
 error:
 	key_ref_put(key_ref);
-
 	return ret;
 }
 

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

queue-4.14/x.509-reject-invalid-bit-string-for-subjectpublickey.patch queue-4.14/asn.1-check-for-error-from-asn1_op_end__act-actions.patch queue-4.14/keys-add-missing-permission-check-for-request_key-destination.patch queue-4.14/asn.1-fix-out-of-bounds-read-when-parsing-indefinite-length-item.patch queue-4.14/keys-reject-null-restriction-string-when-type-is-specified.patch queue-4.14/x.509-fix-comparisons-of-pkey_algo.patch