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From:   Geliang Tang <geliangtang@gmail.com>
To:     David Howells <dhowells@redhat.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>
Cc:     Geliang Tang <geliangtang@gmail.com>, keyrings@vger.kernel.org,
        linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] security: keys: add NULL checking for key->type->instantiate
Date:   Fri, 25 Jan 2019 15:16:14 +0800
Message-Id: <754d6ccb4012fc11c7b9369e66ba7f3e816fdb57.1548400400.git.geliangtang@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

key->type->instantiate can be NULL, add NULL checking to prevent
NULL pointer dereference in __key_instantiate_and_link().

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
---
 security/keys/key.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/keys/key.c b/security/keys/key.c
index 44a80d6741a1..ae3cc11be0d2 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -438,7 +438,8 @@ static int __key_instantiate_and_link(struct key *key,
 	/* can't instantiate twice */
 	if (key->state == KEY_IS_UNINSTANTIATED) {
 		/* instantiate the key */
-		ret = key->type->instantiate(key, prep);
+		if (key->type->instantiate)
+			ret = key->type->instantiate(key, prep);
 
 		if (ret == 0) {
 			/* mark the key as being instantiated */
-- 
2.17.1