diff mbox series

[Openvpn-devel,net] ovpn: fix NULL dereference when killing missing key

Message ID 9fc33e6f9fae10b9e372a3e06934d697edf5b024.1782829171.git.ralf@mandelbit.com
State Superseded
Headers
Series [Openvpn-devel,net] ovpn: fix NULL dereference when killing missing key |

Commit Message

Ralf Lici June 30, 2026, 2:21 p.m. UTC 
  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>
---
 drivers/net/ovpn/crypto.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/net/ovpn/crypto.c b/drivers/net/ovpn/crypto.c
index 90580e32052f..577a22b4e810 100644
--- a/drivers/net/ovpn/crypto.c
+++ b/drivers/net/ovpn/crypto.c
@@ -58,12 +58,18 @@  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;
 
 	spin_lock_bh(&cs->lock);
-	if (rcu_access_pointer(cs->slots[0])->key_id == key_id) {
+	tmp = rcu_access_pointer(cs->slots[0]);
+	if (tmp && tmp->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) {
+	} else {
+		tmp = rcu_access_pointer(cs->slots[1]);
+	}
+
+	if (!ks && tmp && tmp->key_id == key_id) {
 		ks = rcu_replace_pointer(cs->slots[1], NULL,
 					 lockdep_is_held(&cs->lock));
 	}