From e029c9828c5b503b11a609fcc7c5840de2db3fb4 Mon Sep 17 00:00:00 2001
From: Max VA <maxv@sentinelone.com>
Date: Mon, 25 Oct 2021 17:31:53 +0200
Subject: [PATCH] tipc: fix size validations for the MSG_CRYPTO type
Git-commit: fa40d9734a57bcbfa79a280189799f76c88f7bb0
Patch-mainline: v5.15
References: stable-5.14.16 CVE-2021-43267 bsc#1192341

commit fa40d9734a57bcbfa79a280189799f76c88f7bb0 upstream.

The function tipc_crypto_key_rcv is used to parse MSG_CRYPTO messages
to receive keys from other nodes in the cluster in order to decrypt any
further messages from them.
This patch verifies that any supplied sizes in the message body are
valid for the received message.

Fixes: 1ef6f7c9390f ("tipc: add automatic session key exchange")
Signed-off-by: Max VA <maxv@sentinelone.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/tipc/crypto.c | 32 +++++++++++++++++++++-----------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index c9391d38de85..dc60c32bb70d 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -2285,43 +2285,53 @@ static bool tipc_crypto_key_rcv(struct tipc_crypto *rx, struct tipc_msg *hdr)
 	u16 key_gen = msg_key_gen(hdr);
 	u16 size = msg_data_sz(hdr);
 	u8 *data = msg_data(hdr);
+	unsigned int keylen;
+
+	/* Verify whether the size can exist in the packet */
+	if (unlikely(size < sizeof(struct tipc_aead_key) + TIPC_AEAD_KEYLEN_MIN)) {
+		pr_debug("%s: message data size is too small\n", rx->name);
+		goto exit;
+	}
+
+	keylen = ntohl(*((__be32 *)(data + TIPC_AEAD_ALG_NAME)));
+
+	/* Verify the supplied size values */
+	if (unlikely(size != keylen + sizeof(struct tipc_aead_key) ||
+		     keylen > TIPC_AEAD_KEY_SIZE_MAX)) {
+		pr_debug("%s: invalid MSG_CRYPTO key size\n", rx->name);
+		goto exit;
+	}
 
 	spin_lock(&rx->lock);
 	if (unlikely(rx->skey || (key_gen == rx->key_gen && rx->key.keys))) {
 		pr_err("%s: key existed <%p>, gen %d vs %d\n", rx->name,
 		       rx->skey, key_gen, rx->key_gen);
-		goto exit;
+		goto exit_unlock;
 	}
 
 	/* Allocate memory for the key */
 	skey = kmalloc(size, GFP_ATOMIC);
 	if (unlikely(!skey)) {
 		pr_err("%s: unable to allocate memory for skey\n", rx->name);
-		goto exit;
+		goto exit_unlock;
 	}
 
 	/* Copy key from msg data */
-	skey->keylen = ntohl(*((__be32 *)(data + TIPC_AEAD_ALG_NAME)));
+	skey->keylen = keylen;
 	memcpy(skey->alg_name, data, TIPC_AEAD_ALG_NAME);
 	memcpy(skey->key, data + TIPC_AEAD_ALG_NAME + sizeof(__be32),
 	       skey->keylen);
 
-	/* Sanity check */
-	if (unlikely(size != tipc_aead_key_size(skey))) {
-		kfree(skey);
-		skey = NULL;
-		goto exit;
-	}
-
 	rx->key_gen = key_gen;
 	rx->skey_mode = msg_key_mode(hdr);
 	rx->skey = skey;
 	rx->nokey = 0;
 	mb(); /* for nokey flag */
 
-exit:
+exit_unlock:
 	spin_unlock(&rx->lock);
 
+exit:
 	/* Schedule the key attaching on this crypto */
 	if (likely(skey && queue_delayed_work(tx->wq, &rx->work, 0)))
 		return true;
-- 
2.26.2