[PATCH 6.6 011/143] net: mctp: take ownership of skb in mctp_local_output

Greg Kroah-Hartman
2024-03-04T21:36:25Z

From: Jeremy Kerr <jk@codeconstruct.com.au>

[ Upstream commit 3773d65ae5154ed7df404b050fd7387a36ab5ef3 ]

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@codeconstruct.com.au>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240220081053.1439104-1-jk@codeconstruct.com.au
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/mctp.h | 1 +
net/mctp/route.c | 10 ++++++++--
2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/net/mctp.h b/include/net/mctp.h
index da86e106c91d5..2bff5f47ce82f 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 6218dcd07e184..ceee44ea09d97 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 +903,8 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
rt->mtu = 0;

} else {
- return -EINVAL;
+ rc = -EINVAL;
+ goto out_free;
}

spin_lock_irqsave(&rt->dev->addrs_lock, flags);
@@ -966,12 +967,17 @@ 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;
}

--
2.43.0