From 027421cbd2e6e628f5f959c74d722afadc477485 Mon Sep 17 00:00:00 2001
From: Tobias Brunner <tobias@strongswan.org>
Date: Tue, 11 Jul 2023 12:12:25 +0200
Subject: [PATCH] charon-tkm: Validate DH public key to fix potential buffer
 overflow

Seems this was forgotten in the referenced commit and actually could lead
to a buffer overflow.  Since charon-tkm is untrusted this isn't that
much of an issue but could at least be easily exploited for a DoS attack
as DH public values are set when handling IKE_SA_INIT requests.

Fixes: 0356089d0f94 ("diffie-hellman: Verify public DH values in backends")
Fixes: CVE-2023-41913
---
 src/charon-tkm/src/tkm/tkm_diffie_hellman.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/charon-tkm/src/tkm/tkm_diffie_hellman.c b/src/charon-tkm/src/tkm/tkm_diffie_hellman.c
index 2b2d103d03e9..6999ad360d7e 100644
--- a/src/charon-tkm/src/tkm/tkm_diffie_hellman.c
+++ b/src/charon-tkm/src/tkm/tkm_diffie_hellman.c
@@ -70,11 +70,16 @@ METHOD(key_exchange_t, get_shared_secret, bool,
 	return TRUE;
 }
 
-
 METHOD(key_exchange_t, set_public_key, bool,
 	private_tkm_diffie_hellman_t *this, chunk_t value)
 {
 	dh_pubvalue_type othervalue;
+
+	if (!key_exchange_verify_pubkey(this->group, value) ||
+		value.len > sizeof(othervalue.data))
+	{
+		return FALSE;
+	}
 	othervalue.size = value.len;
 	memcpy(&othervalue.data, value.ptr, value.len);
 
-- 
2.34.1

