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AFNElJ8081KExYWsDdGIq42ihG63qkZCzNKmlCeWH4n3BtBRV0vbg2X0AtxN8qV/weSghtysqAGxaYFiQ7vV9WQ=@vger.kernel.org X-Gm-Message-State: AOJu0Yw5FIKcxF1ytSfoxvxTpWI5y5tX4v6dsAGQXwKjaR9lub3EVH0y gyM80vkr/JmtUvV2YPmDV+VT12KyWYYGrgM7WnV3aYn2G1NAwFkdiPQkDjVxvM1Z/OawADy/6qw j61jmqIJciJB7zdDt75hFxtEfd59+tjshcHlKyDvBiAFXs9+RUSbyiGNWiUQ= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1885:b0:694:980c:9606 with SMTP id 006d021491bc7-69697dfb0dfmr4449543eaf.32.1777893241517; Mon, 04 May 2026 04:14:01 -0700 (PDT) Date: Mon, 04 May 2026 04:14:01 -0700 In-Reply-To: <67030b5e-0435-49fc-8adb-8dd8536ad853@kernel.org> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69f87f79.050a0220.3460d5.0002.GAE@google.com> Subject: Re: [syzbot] [mptcp?] KMSAN: uninit-value in mptcp_established_options From: syzbot To: kuniyu@google.com, linux-kernel@vger.kernel.org, matttbe@kernel.org, mptcp@lists.linux.dev, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: KMSAN: uninit-value in mptcp_write_options ===================================================== BUG: KMSAN: uninit-value in mptcp_write_options+0x410/0x32e0 net/mptcp/options.c:1462 mptcp_write_options+0x410/0x32e0 net/mptcp/options.c:1462 mptcp_options_write net/ipv4/tcp_output.c:457 [inline] tcp_options_write+0x1399/0x1920 net/ipv4/tcp_output.c:833 __tcp_transmit_skb+0x36fe/0x5fe0 net/ipv4/tcp_output.c:1656 __tcp_send_ack+0x967/0xad0 net/ipv4/tcp_output.c:4499 tcp_send_ack+0x3d/0x60 net/ipv4/tcp_output.c:4505 __mptcp_subflow_send_ack net/mptcp/protocol.c:538 [inline] mptcp_subflow_send_ack net/mptcp/protocol.c:546 [inline] mptcp_send_ack net/mptcp/protocol.c:555 [inline] mptcp_check_data_fin+0xa61/0xf00 net/mptcp/protocol.c:643 mptcp_worker+0xde4/0x1ea0 net/mptcp/protocol.c:2980 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3385 worker_thread+0xee4/0x1590 kernel/workqueue.c:3466 kthread+0x53f/0x600 kernel/kthread.c:436 ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Uninit was stored to memory at: mptcp_established_options_dss net/mptcp/options.c:616 [inline] mptcp_established_options+0x2265/0x3580 net/mptcp/options.c:876 tcp_established_options+0x312/0xcc0 net/ipv4/tcp_output.c:1192 __tcp_transmit_skb+0x5dc/0x5fe0 net/ipv4/tcp_output.c:1575 __tcp_send_ack+0x967/0xad0 net/ipv4/tcp_output.c:4499 tcp_send_ack+0x3d/0x60 net/ipv4/tcp_output.c:4505 __mptcp_subflow_send_ack net/mptcp/protocol.c:538 [inline] mptcp_subflow_send_ack net/mptcp/protocol.c:546 [inline] mptcp_send_ack net/mptcp/protocol.c:555 [inline] mptcp_check_data_fin+0xa61/0xf00 net/mptcp/protocol.c:643 mptcp_worker+0xde4/0x1ea0 net/mptcp/protocol.c:2980 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3385 worker_thread+0xee4/0x1590 kernel/workqueue.c:3466 kthread+0x53f/0x600 kernel/kthread.c:436 ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Local variable opts created at: __tcp_transmit_skb+0x4d/0x5fe0 net/ipv4/tcp_output.c:1536 __tcp_send_ack+0x967/0xad0 net/ipv4/tcp_output.c:4499 CPU: 0 UID: 0 PID: 4890 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: events mptcp_worker ===================================================== Tested on: commit: 6d35786d Merge tag 'for-linus' of git://git.kernel.org.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=123d6696580000 kernel config: https://syzkaller.appspot.com/x/.config?x=1c3f61154f3bb7e5 dashboard link: https://syzkaller.appspot.com/bug?extid=ff020673c5e3d94d9478 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 patch: https://syzkaller.appspot.com/x/patch.diff?x=1663f21f980000