From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C1D862FB622; Tue, 30 Sep 2025 14:50:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759243853; cv=none; b=VgvPe27v+5Dn4CRT0Em2vv1uADuqJ6V7hxFvcX0gahF1tLfV4bMVeLCXJsG522A4UbbMp1PCs7iCVeCcp3s3uHu3+si+mD8VBngul3YbJe0Qq2Mg3cdQaofEOlQH0vxsZPD+rBgs7Gw/yePqoSb1blYikfOw8RDDrP3tff2Ol2c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759243853; c=relaxed/simple; bh=yarexIHggS+xS54IXZ0pOzup5t83RY5zcIaVjX4p+Qo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WmO/L7dgugmtvkYr6zpLUQjINpWUHuCyaKqh2D/nRdwzk7SEO2Z47WOhjOlFZqWcdmwUbxMU2aT5E6h/H/EyJ0sCq9FxmSEG+bIK1WvoNRWXo4TLJ9GXwDSMbuRecv5FgIs4d0r2joyamA9SPTxujMWXhgf+Hf+8+eIfOZs3Jnk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=S6HaJPzk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="S6HaJPzk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 409DCC4CEF0; Tue, 30 Sep 2025 14:50:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1759243853; bh=yarexIHggS+xS54IXZ0pOzup5t83RY5zcIaVjX4p+Qo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S6HaJPzkrNgyUM9+i/XqKTo+QPom5ZrOTKcrwDAqCBsaPUjmqfaAZ5byCwtWOAySG m/zjlWe4Yyg39GnALFtVPI7WecSppBAQ7xMMI2eVc/pZ9OAYVZBDu3sEpaTansNpR2 v+eaomEL+Bp4aV8Tspy95JlGAQ6pB5ga4wur/8es= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzkaller , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 5.4 37/81] tcp: Clear tcp_sk(sk)->fastopen_rsk in tcp_disconnect(). Date: Tue, 30 Sep 2025 16:46:39 +0200 Message-ID: <20250930143821.227273631@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250930143819.654157320@linuxfoundation.org> References: <20250930143819.654157320@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01 ] syzbot reported the splat below where a socket had tcp_sk(sk)->fastopen_rsk in the TCP_ESTABLISHED state. [0] syzbot reused the server-side TCP Fast Open socket as a new client before the TFO socket completes 3WHS: 1. accept() 2. connect(AF_UNSPEC) 3. connect() to another destination As of accept(), sk->sk_state is TCP_SYN_RECV, and tcp_disconnect() changes it to TCP_CLOSE and makes connect() possible, which restarts timers. Since tcp_disconnect() forgot to clear tcp_sk(sk)->fastopen_rsk, the retransmit timer triggered the warning and the intended packet was not retransmitted. Let's call reqsk_fastopen_remove() in tcp_disconnect(). [0]: WARNING: CPU: 2 PID: 0 at net/ipv4/tcp_timer.c:542 tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7)) Modules linked in: CPU: 2 UID: 0 PID: 0 Comm: swapper/2 Not tainted 6.17.0-rc5-g201825fb4278 #62 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:tcp_retransmit_timer (net/ipv4/tcp_timer.c:542 (discriminator 7)) Code: 41 55 41 54 55 53 48 8b af b8 08 00 00 48 89 fb 48 85 ed 0f 84 55 01 00 00 0f b6 47 12 3c 03 74 0c 0f b6 47 12 3c 04 74 04 90 <0f> 0b 90 48 8b 85 c0 00 00 00 48 89 ef 48 8b 40 30 e8 6a 4f 06 3e RSP: 0018:ffffc900002f8d40 EFLAGS: 00010293 RAX: 0000000000000002 RBX: ffff888106911400 RCX: 0000000000000017 RDX: 0000000002517619 RSI: ffffffff83764080 RDI: ffff888106911400 RBP: ffff888106d5c000 R08: 0000000000000001 R09: ffffc900002f8de8 R10: 00000000000000c2 R11: ffffc900002f8ff8 R12: ffff888106911540 R13: ffff888106911480 R14: ffff888106911840 R15: ffffc900002f8de0 FS: 0000000000000000(0000) GS:ffff88907b768000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f8044d69d90 CR3: 0000000002c30003 CR4: 0000000000370ef0 Call Trace: tcp_write_timer (net/ipv4/tcp_timer.c:738) call_timer_fn (kernel/time/timer.c:1747) __run_timers (kernel/time/timer.c:1799 kernel/time/timer.c:2372) timer_expire_remote (kernel/time/timer.c:2385 kernel/time/timer.c:2376 kernel/time/timer.c:2135) tmigr_handle_remote_up (kernel/time/timer_migration.c:944 kernel/time/timer_migration.c:1035) __walk_groups.isra.0 (kernel/time/timer_migration.c:533 (discriminator 1)) tmigr_handle_remote (kernel/time/timer_migration.c:1096) handle_softirqs (./arch/x86/include/asm/jump_label.h:36 ./include/trace/events/irq.h:142 kernel/softirq.c:580) irq_exit_rcu (kernel/softirq.c:614 kernel/softirq.c:453 kernel/softirq.c:680 kernel/softirq.c:696) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1050 (discriminator 35) arch/x86/kernel/apic/apic.c:1050 (discriminator 35)) Fixes: 8336886f786f ("tcp: TCP Fast Open Server - support TFO listeners") Reported-by: syzkaller Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250915175800.118793-2-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/tcp.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 55754bf176d99..cc0efcb4a553c 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2593,6 +2593,7 @@ int tcp_disconnect(struct sock *sk, int flags) struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); int old_state = sk->sk_state; + struct request_sock *req; u32 seq; /* Deny disconnect if other threads are blocked in sk_wait_event() @@ -2711,6 +2712,10 @@ int tcp_disconnect(struct sock *sk, int flags) /* Clean up fastopen related fields */ + req = rcu_dereference_protected(tp->fastopen_rsk, + lockdep_sock_is_held(sk)); + if (req) + reqsk_fastopen_remove(sk, req, false); tcp_free_fastopen_req(tp); inet->defer_connect = 0; tp->fastopen_client_fail = 0; -- 2.51.0