Merge branch 'mptcp-misc-fixes-for-6-15-rc0'

Matthieu Baerts says:

====================
mptcp: misc. fixes for 6.15-rc0

Here are 4 unrelated patches:

- Patch 1: fix a NULL pointer when two SYN-ACK for the same request are
  handled in parallel. A fix for up to v5.9.

- Patch 2: selftests: fix check for the wrong FD. A fix for up to v5.17.

- Patch 3: selftests: close all FDs in case of error. A fix for up to
  v5.17.

- Patch 4: selftests: ignore a new generated file. A fix for 6.15-rc0.
====================

Link: https://patch.msgid.link/20250328-net-mptcp-misc-fixes-6-15-v1-0-34161a482a7f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 16 insertions, 11 deletions

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index efe8d86496db..409bd415ef1d 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -754,8 +754,6 @@ static bool subflow_hmac_valid(const struct request_sock *req,
 
 	subflow_req = mptcp_subflow_rsk(req);
 	msk = subflow_req->msk;
-	if (!msk)
-		return false;
 
 	subflow_generate_hmac(READ_ONCE(msk->remote_key),
 			      READ_ONCE(msk->local_key),
@@ -850,12 +848,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 
 	} else if (subflow_req->mp_join) {
 		mptcp_get_options(skb, &mp_opt);
-		if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) ||
-		    !subflow_hmac_valid(req, &mp_opt) ||
-		    !mptcp_can_accept_new_subflow(subflow_req->msk)) {
-			SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
+		if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK))
 			fallback = true;
-		}
 	}
 
 create_child:
@@ -905,6 +899,13 @@ create_child:
 				goto dispose_child;
 			}
 
+			if (!subflow_hmac_valid(req, &mp_opt) ||
+			    !mptcp_can_accept_new_subflow(subflow_req->msk)) {
+				SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
+				subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
+				goto dispose_child;
+			}
+
 			/* move the msk reference ownership to the subflow */
 			subflow_req->msk = NULL;
 			ctx->conn = (struct sock *)owner;
diff --git a/tools/testing/selftests/net/mptcp/.gitignore b/tools/testing/selftests/net/mptcp/.gitignore
index 49daae73c41e..833279fb34e2 100644
--- a/tools/testing/selftests/net/mptcp/.gitignore
+++ b/tools/testing/selftests/net/mptcp/.gitignore
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
 mptcp_connect
+mptcp_diag
 mptcp_inq
 mptcp_sockopt
 pm_nl_ctl
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.c b/tools/testing/selftests/net/mptcp/mptcp_connect.c
index d240d02fa443..c83a8b47bbdf 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.c
@@ -1270,7 +1270,7 @@ int main_loop(void)
 
 	if (cfg_input && cfg_sockopt_types.mptfo) {
 		fd_in = open(cfg_input, O_RDONLY);
-		if (fd < 0)
+		if (fd_in < 0)
 			xerror("can't open %s:%d", cfg_input, errno);
 	}
 
@@ -1293,13 +1293,13 @@ again:
 
 	if (cfg_input && !cfg_sockopt_types.mptfo) {
 		fd_in = open(cfg_input, O_RDONLY);
-		if (fd < 0)
+		if (fd_in < 0)
 			xerror("can't open %s:%d", cfg_input, errno);
 	}
 
 	ret = copyfd_io(fd_in, fd, 1, 0, &winfo);
 	if (ret)
-		return ret;
+		goto out;
 
 	if (cfg_truncate > 0) {
 		shutdown(fd, SHUT_WR);
@@ -1320,7 +1320,10 @@ again:
 		close(fd);
 	}
 
-	return 0;
+out:
+	if (cfg_input)
+		close(fd_in);
+	return ret;
 }
 
 int parse_proto(const char *proto)