From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Ralf Lici <ralf@mandelbit.com>,
	Antonio Quartulli <antonio@openvpn.net>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 7.1 173/228] ovpn: fix NULL dereference when killing missing key
Date: Thu, 20 Aug 2026 16:55:15 +0200
Message-ID: <20260820145249.950871428@linuxfoundation.org>
In-Reply-To: <20260820145244.450574346@linuxfoundation.org>
References: <20260820145244.450574346@linuxfoundation.org>
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7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ralf Lici <ralf@mandelbit.com>

[ Upstream commit 41d44ac7a61e2f74453af40d4fe1b82af9ea0ada ]

ovpn_crypto_kill_key assumes both crypto slots are populated and
dereferences each slot before checking it. That is not guaranteed: a
peer can have only one installed key, and the kill path may be asked to
remove a key that is not present.

Read each slot once while holding the crypto state lock, check for NULL
before looking at key_id, and only replace the slot that actually
matches.

Fixes: 89d3c0e4612a ("ovpn: kill key and notify userspace in case of IV exhaustion")
Signed-off-by: Ralf Lici <ralf@mandelbit.com>
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ovpn/crypto.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ovpn/crypto.c b/drivers/net/ovpn/crypto.c
index 90580e32052fb..2e95f29514fc4 100644
--- a/drivers/net/ovpn/crypto.c
+++ b/drivers/net/ovpn/crypto.c
@@ -58,15 +58,19 @@ void ovpn_crypto_state_release(struct ovpn_crypto_state *cs)
 bool ovpn_crypto_kill_key(struct ovpn_crypto_state *cs, u8 key_id)
 {
 	struct ovpn_crypto_key_slot *ks = NULL;
+	struct ovpn_crypto_key_slot *tmp;
+	int slot = 0;
 
 	spin_lock_bh(&cs->lock);
-	if (rcu_access_pointer(cs->slots[0])->key_id == key_id) {
-		ks = rcu_replace_pointer(cs->slots[0], NULL,
-					 lockdep_is_held(&cs->lock));
-	} else if (rcu_access_pointer(cs->slots[1])->key_id == key_id) {
-		ks = rcu_replace_pointer(cs->slots[1], NULL,
-					 lockdep_is_held(&cs->lock));
+	tmp = rcu_access_pointer(cs->slots[slot]);
+	if (!tmp || tmp->key_id != key_id) {
+		slot = 1;
+		tmp = rcu_access_pointer(cs->slots[slot]);
 	}
+
+	if (tmp && tmp->key_id == key_id)
+		ks = rcu_replace_pointer(cs->slots[slot], NULL,
+					 lockdep_is_held(&cs->lock));
 	spin_unlock_bh(&cs->lock);
 
 	if (ks)
-- 
2.53.0