linux-kernel - [PATCH v2 2/3] KEYS: don't revoke uninstantiated key in request_key_auth

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Date:   Thu, 21 Sep 2017 13:57:41 -0700
From:   Eric Biggers <ebiggers3@...il.com>
To:     keyrings@...r.kernel.org
Cc:     David Howells <dhowells@...hat.com>,
        Michael Halcrow <mhalcrow@...gle.com>,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH v2 2/3] KEYS: don't revoke uninstantiated key in request_key_auth_new()

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

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>
---
 security/keys/request_key_auth.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index 8f12645945ca..2df92b619a38 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -220,7 +220,6 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
 	return authkey;
 
 error_put_authkey:
-	key_revoke(authkey);
 	key_put(authkey);
 error_free_rka:
 	free_request_key_auth(rka);
-- 
2.14.1.821.g8fa685d3b7-goog