Re: [PATCH v2] tipc: check for null after calling kmemdup

kmemdup can return a null pointer so need to check for it, otherwise
the null key will be dereferenced later in tipc_crypto_key_xmit as
can be seen in the trace [1].

Cc: Jon Maloy <jmaloy@redhat.com>
Cc: Ying Xue <redacted>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Cc: tipc-discussion@lists.sourceforge.net
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org # 5.15, 5.14, 5.10

[1] https://syzkaller.appspot.com/bug?id=bca180abb29567b189efdbdb34cbf7ba851c2a58

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Tadeusz Struk <redacted>
---
Changed in v2:
- use tipc_aead_free() to free all crytpo tfm instances
   that might have been allocated before the fail.
---
  net/tipc/crypto.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index dc60c32bb70d..d293614d5fc6 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c

@@ -597,6 +597,10 @@ static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
  	tmp->cloned = NULL;
  	tmp->authsize = TIPC_AES_GCM_TAG_SIZE;
  	tmp->key = kmemdup(ukey, tipc_aead_key_size(ukey), GFP_KERNEL);
+	if (!tmp->key) {
+		tipc_aead_free(&tmp->rcu);
+		return -ENOMEM;
+	}
  	memcpy(&tmp->salt, ukey->key + keylen, TIPC_AES_GCM_SALT_SIZE);
  	atomic_set(&tmp->users, 0);
  	atomic64_set(&tmp->seqno, 0);