Patch "net: mctp: mark socks as dead on unhash, prevent re-add" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-mctp-mark-socks-as-dead-on-unhash-prevent-re-add.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit f89bd2af414083464eba0ea996ffe0a4fc699408
Author: Jeremy Kerr <jk@xxxxxxxxxxxxxxxxxxxx>
Date:   Tue Jan 24 10:01:06 2023 +0800

    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@xxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/mctp/af_mctp.c b/net/mctp/af_mctp.c
index fb6ae3110528..45bbe3e54cc2 100644
--- a/net/mctp/af_mctp.c
+++ b/net/mctp/af_mctp.c
@@ -577,6 +577,7 @@ static void mctp_sk_unhash(struct sock *sk)
 		spin_lock_irqsave(&key->lock, fl2);
 		__mctp_key_remove(key, net, fl2, MCTP_TRACE_KEY_CLOSED);
 	}
+	sock_set_flag(sk, SOCK_DEAD);
 	spin_unlock_irqrestore(&net->mctp.keys_lock, flags);
 
 	/* Since there are no more tag allocations (we have removed all of the
diff --git a/net/mctp/route.c b/net/mctp/route.c
index 06c0de21984d..f51a05ec7162 100644
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -179,6 +179,11 @@ 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)) {
@@ -200,6 +205,7 @@ 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;