linux-kernel - [PATCH 3.2 20/94] KEYS: don't revoke uninstantiated key in request_key_auth

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Message-ID: <lsq.1514480352.155808345@decadent.org.uk>
Date:   Thu, 28 Dec 2017 16:59:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "David Howells" <dhowells@...hat.com>,
        "Eric Biggers" <ebiggers@...gle.com>
Subject: [PATCH 3.2 20/94] KEYS: don't revoke uninstantiated key in
 request_key_auth_new()

3.2.97-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@...gle.com>

commit f7b48cf08fa63a68b59c2894806ee478216d7f91 upstream.

If key_instantiate_and_link() were to fail (which fortunately isn't
possible currently), the call to key_revoke(authkey) would crash with a
NULL pointer dereference in request_key_auth_revoke() because the key
has not yet been instantiated.

Fix this by removing the call to key_revoke().  key_put() is sufficient,
as it's not possible for an uninstantiated authkey to have been used for
anything yet.

Fixes: b5f545c880a2 ("[PATCH] keys: Permit running process to instantiate keys")
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 security/keys/request_key_auth.c | 1 -
 1 file changed, 1 deletion(-)

--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -206,7 +206,6 @@ struct key *request_key_auth_new(struct
 	return authkey;
 
 error_put_authkey:
-	key_revoke(authkey);
 	key_put(authkey);
 error_free_rka:
 	free_request_key_auth(rka);