net: mctp: mark socks as dead on unhash, prevent re-add

[ Upstream commit b98e1a04e27fddfdc808bf46fe78eca30db89ab3 ]

Once a socket has been unhashed, we want to prevent it from being
re-used in a sk_key entry as part of a routing operation.

This change marks the sk as SOCK_DEAD on unhash, which prevents addition
into the net's key list.

We need to do this during the key add path, rather than key lookup, as
we release the net keys_lock between those operations.

Fixes: 4a992bbd3650 ("mctp: Implement message fragmentation & reassembly")
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/mctp/af_mctp.c b/net/mctp/af_mctp.c
index cbbde0f..a77fafb 100644 (file)
--- a/net/mctp/af_mctp.c
+++ b/net/mctp/af_mctp.c
@@ -288,6 +288,7 @@ static void mctp_sk_unhash(struct sock *sk)
 
                kfree_rcu(key, rcu);
        }
+       sock_set_flag(sk, SOCK_DEAD);
        spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
 
        synchronize_rcu();

diff --git a/net/mctp/route.c b/net/mctp/route.c
index 6aebb4a..89e6739 100644 (file)
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -135,6 +135,11 @@ static int mctp_key_add(struct mctp_sk_key *key, struct mctp_sock *msk)
 
        spin_lock_irqsave(&net->mctp.keys_lock, flags);
 
+       if (sock_flag(&msk->sk, SOCK_DEAD)) {
+               rc = -EINVAL;
+               goto out_unlock;
+       }
+
        hlist_for_each_entry(tmp, &net->mctp.keys, hlist) {
                if (mctp_key_match(tmp, key->local_addr, key->peer_addr,
                                   key->tag)) {
@@ -148,6 +153,7 @@ static int mctp_key_add(struct mctp_sk_key *key, struct mctp_sock *msk)
                hlist_add_head(&key->sklist, &msk->keys);
        }
 
+out_unlock:
        spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
 
        return rc;