--- /dev/null
+From stable+bounces-206040-greg=kroah.com@vger.kernel.org Tue Jan 6 21:57:33 2026
+From: Sasha Levin <sashal@kernel.org>
+Date: Tue, 6 Jan 2026 15:55:58 -0500
+Subject: mptcp: ensure context reset on disconnect()
+To: stable@vger.kernel.org
+Cc: Paolo Abeni <pabeni@redhat.com>, "Matthieu Baerts (NGI0)" <matttbe@kernel.org>, Sasha Levin <sashal@kernel.org>
+Message-ID: <20260106205558.3365755-1-sashal@kernel.org>
+
+From: Paolo Abeni <pabeni@redhat.com>
+
+[ Upstream commit 86730ac255b0497a272704de9a1df559f5d6602e ]
+
+After the blamed commit below, if the MPC subflow is already in TCP_CLOSE
+status or has fallback to TCP at mptcp_disconnect() time,
+mptcp_do_fastclose() skips setting the `send_fastclose flag` and the later
+__mptcp_close_ssk() does not reset anymore the related subflow context.
+
+Any later connection will be created with both the `request_mptcp` flag
+and the msk-level fallback status off (it is unconditionally cleared at
+MPTCP disconnect time), leading to a warning in subflow_data_ready():
+
+ WARNING: CPU: 26 PID: 8996 at net/mptcp/subflow.c:1519 subflow_data_ready (net/mptcp/subflow.c:1519 (discriminator 13))
+ Modules linked in:
+ CPU: 26 UID: 0 PID: 8996 Comm: syz.22.39 Not tainted 6.18.0-rc7-05427-g11fc074f6c36 #1 PREEMPT(voluntary)
+ Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
+ RIP: 0010:subflow_data_ready (net/mptcp/subflow.c:1519 (discriminator 13))
+ Code: 90 0f 0b 90 90 e9 04 fe ff ff e8 b7 1e f5 fe 89 ee bf 07 00 00 00 e8 db 19 f5 fe 83 fd 07 0f 84 35 ff ff ff e8 9d 1e f5 fe 90 <0f> 0b 90 e9 27 ff ff ff e8 8f 1e f5 fe 4c 89 e7 48 89 de e8 14 09
+ RSP: 0018:ffffc9002646fb30 EFLAGS: 00010293
+ RAX: 0000000000000000 RBX: ffff88813b218000 RCX: ffffffff825c8435
+ RDX: ffff8881300b3580 RSI: ffffffff825c8443 RDI: 0000000000000005
+ RBP: 000000000000000b R08: ffffffff825c8435 R09: 000000000000000b
+ R10: 0000000000000005 R11: 0000000000000007 R12: ffff888131ac0000
+ R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
+ FS: 00007f88330af6c0(0000) GS:ffff888a93dd2000(0000) knlGS:0000000000000000
+ CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+ CR2: 00007f88330aefe8 CR3: 000000010ff59000 CR4: 0000000000350ef0
+ Call Trace:
+ <TASK>
+ tcp_data_ready (net/ipv4/tcp_input.c:5356)
+ tcp_data_queue (net/ipv4/tcp_input.c:5445)
+ tcp_rcv_state_process (net/ipv4/tcp_input.c:7165)
+ tcp_v4_do_rcv (net/ipv4/tcp_ipv4.c:1955)
+ __release_sock (include/net/sock.h:1158 (discriminator 6) net/core/sock.c:3180 (discriminator 6))
+ release_sock (net/core/sock.c:3737)
+ mptcp_sendmsg (net/mptcp/protocol.c:1763 net/mptcp/protocol.c:1857)
+ inet_sendmsg (net/ipv4/af_inet.c:853 (discriminator 7))
+ __sys_sendto (net/socket.c:727 (discriminator 15) net/socket.c:742 (discriminator 15) net/socket.c:2244 (discriminator 15))
+ __x64_sys_sendto (net/socket.c:2247)
+ do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
+ entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
+ RIP: 0033:0x7f883326702d
+
+Address the issue setting an explicit `fastclosing` flag at fastclose
+time, and checking such flag after mptcp_do_fastclose().
+
+Fixes: ae155060247b ("mptcp: fix duplicate reset on fastclose")
+Cc: stable@vger.kernel.org
+Signed-off-by: Paolo Abeni <pabeni@redhat.com>
+Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
+Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
+Link: https://patch.msgid.link/20251212-net-mptcp-subflow_data_ready-warn-v1-2-d1f9fd1c36c8@kernel.org
+Signed-off-by: Paolo Abeni <pabeni@redhat.com>
+[ Adjust context ]
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ net/mptcp/protocol.c | 8 +++++---
+ net/mptcp/protocol.h | 3 ++-
+ 2 files changed, 7 insertions(+), 4 deletions(-)
+
+--- a/net/mptcp/protocol.c
++++ b/net/mptcp/protocol.c
+@@ -2421,10 +2421,10 @@ bool __mptcp_retransmit_pending_data(str
+ */
+ static void __mptcp_subflow_disconnect(struct sock *ssk,
+ struct mptcp_subflow_context *subflow,
+- unsigned int flags)
++ bool fastclosing)
+ {
+ if (((1 << ssk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN)) ||
+- subflow->send_fastclose) {
++ fastclosing) {
+ /* The MPTCP code never wait on the subflow sockets, TCP-level
+ * disconnect should never fail
+ */
+@@ -2476,7 +2476,7 @@ static void __mptcp_close_ssk(struct soc
+
+ need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk);
+ if (!dispose_it) {
+- __mptcp_subflow_disconnect(ssk, subflow, flags);
++ __mptcp_subflow_disconnect(ssk, subflow, msk->fastclosing);
+ release_sock(ssk);
+
+ goto out;
+@@ -2789,6 +2789,7 @@ static void mptcp_do_fastclose(struct so
+ struct mptcp_sock *msk = mptcp_sk(sk);
+
+ mptcp_set_state(sk, TCP_CLOSE);
++ msk->fastclosing = 1;
+
+ /* Explicitly send the fastclose reset as need */
+ if (__mptcp_check_fallback(msk))
+@@ -3299,6 +3300,7 @@ static int mptcp_disconnect(struct sock
+ msk->bytes_sent = 0;
+ msk->bytes_retrans = 0;
+ msk->rcvspace_init = 0;
++ msk->fastclosing = 0;
+
+ WRITE_ONCE(sk->sk_shutdown, 0);
+ sk_error_report(sk);
+--- a/net/mptcp/protocol.h
++++ b/net/mptcp/protocol.h
+@@ -321,7 +321,8 @@ struct mptcp_sock {
+ fastopening:1,
+ in_accept_queue:1,
+ free_first:1,
+- rcvspace_init:1;
++ rcvspace_init:1,
++ fastclosing:1;
+ u32 notsent_lowat;
+ int keepalive_cnt;
+ int keepalive_idle;
projects / thirdparty / kernel / stable-queue.git / commitdiff
