[PATCH][next] mptcp: Avoid NULL dereference in mptcp_getsockopt_subflow_addrs()

Tim Gardner
2021-09-20T15:42:50Z

Coverity complains of a possible NULL dereference in
mptcp_getsockopt_subflow_addrs():

861 } else if (sk->sk_family == AF_INET6) {
3. returned_null: inet6_sk returns NULL. [show details]
4. var_assigned: Assigning: np = NULL return value from inet6_sk.
862 const struct ipv6_pinfo *np = inet6_sk(sk);

Fix this by checking for NULL.

Cc: Mat Martineau <mathew.j.martineau@linux.intel.com>
Cc: Matthieu Baerts <matthieu.baerts@tessares.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Cc: mptcp@lists.linux.dev
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

[ I'm not at all sure this is the right thing to do since the final result is to
return garbage to user space in mptcp_getsockopt_subflow_addrs(). Is this one
of those cases where inet6_sk() can't fail ?]
---
net/mptcp/sockopt.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 8137cc3a4296..c89f2bedce79 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -861,6 +861,9 @@ static void mptcp_get_sub_addrs(const struct sock *sk, struct mptcp_subflow_addr
} else if (sk->sk_family == AF_INET6) {
const struct ipv6_pinfo *np = inet6_sk(sk);

+ if (!np)
+ return;
+
a->sin6_local.sin6_family = AF_INET6;
a->sin6_local.sin6_port = inet->inet_sport;

--
2.33.0