netdev - [PATCH net] net: mctp: take ownership of skb in mctp_local

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <f05c0c62d33fda70c7443287b2769d3eb1b3356c.1707983334.git.jk@codeconstruct.com.au>
Date: Thu, 15 Feb 2024 15:53:09 +0800
From: Jeremy Kerr <jk@...econstruct.com.au>
To: netdev@...r.kernel.org
Cc: Matt Johnston <matt@...econstruct.com.au>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net] net: mctp: take ownership of skb in mctp_local_output

Currently, mctp_local_output only takes ownership of skb on success, and
we may leak an skb if mctp_local_output fails in specific states; the
skb ownership isn't transferred until the actual output routing occurs.

Instead, make mctp_local_output free the skb on all error paths up to
the route action, so it always consumes the passed skb.

Fixes: 833ef3b91de6 ("mctp: Populate socket implementation")
Signed-off-by: Jeremy Kerr <jk@...econstruct.com.au>
---
 include/net/mctp.h | 1 +
 net/mctp/route.c   | 9 +++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/net/mctp.h b/include/net/mctp.h
index da86e106c91d..2bff5f47ce82 100644
--- a/include/net/mctp.h
+++ b/include/net/mctp.h
@@ -249,6 +249,7 @@ struct mctp_route {
 struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet,
 				     mctp_eid_t daddr);
 
+/* always takes ownership of skb */
 int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 		      struct sk_buff *skb, mctp_eid_t daddr, u8 req_tag);
 
diff --git a/net/mctp/route.c b/net/mctp/route.c
index 7a47a58aa54b..a64788bc40a8 100644
--- a/net/mctp/route.c
+++ b/net/mctp/route.c
@@ -888,7 +888,7 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 		dev = dev_get_by_index_rcu(sock_net(sk), cb->ifindex);
 		if (!dev) {
 			rcu_read_unlock();
-			return rc;
+			goto out_free;
 		}
 		rt->dev = __mctp_dev_get(dev);
 		rcu_read_unlock();
@@ -903,7 +903,7 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 		rt->mtu = 0;
 
 	} else {
-		return -EINVAL;
+		goto out_free;
 	}
 
 	spin_lock_irqsave(&rt->dev->addrs_lock, flags);
@@ -966,12 +966,17 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
 		rc = mctp_do_fragment_route(rt, skb, mtu, tag);
 	}
 
+	/* route output functions consume the skb, even on error */
+	skb = NULL;
+
 out_release:
 	if (!ext_rt)
 		mctp_route_release(rt);
 
 	mctp_dev_put(tmp_rt.dev);
 
+out_free:
+	kfree_skb(skb);
 	return rc;
 }
 
-- 
2.39.2