netdev - [PATCH] mctp: Avoid leak of mctp_sk

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Message-Id: <20211014074428.3007121-1-matt@codeconstruct.com.au>
Date:   Thu, 14 Oct 2021 15:44:28 +0800
From:   Matt Johnston <matt@...econstruct.com.au>
To:     netdev@...r.kernel.org
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Jeremy Kerr <jk@...econstruct.com.au>
Subject: [PATCH] mctp: Avoid leak of mctp_sk_key

mctp_key_alloc() returns a key already referenced.

The mctp_route_input() path receives a packet for a bind socket and
allocates a key. It passes the key to mctp_key_add() which takes a
refcount and adds the key to lists. mctp_route_input() should then
release its own refcount when setting the key pointer to NULL.

In the mctp_alloc_local_tag() path (for mctp_local_output()) we
similarly need to unref the key before returning (mctp_reserve_tag()
takes a refcount and adds the key to lists).

Fixes: 73c618456dc ("mctp: locking, lifetime and validity changes for sk_keys")
Signed-off-by: Matt Johnston <matt@...econstruct.com.au>
Reviewed-by: Jeremy Kerr <jk@...econstruct.com.au>
---
 net/mctp/route.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/mctp/route.c b/net/mctp/route.c
index 04781459b2be..82fb5ae524f6 100644
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -372,6 +372,7 @@ static int mctp_route_input(struct mctp_route *route, struct sk_buff *skb)
 			trace_mctp_key_acquire(key);
 
 			/* we don't need to release key->lock on exit */
+			mctp_key_unref(key);
 			key = NULL;
 
 		} else {
@@ -584,6 +585,9 @@ static int mctp_alloc_local_tag(struct mctp_sock *msk,
 		trace_mctp_key_acquire(key);
 
 		*tagp = key->tag;
+		/* done with the key in this scope */
+		mctp_key_unref(key);
+		key = NULL;
 		rc = 0;
 	}
 
-- 
2.30.2