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AFNElJ/MJvfIQ52zcGowe/1fI2IRIqQxZ8TvdLfycmqRlKnFH2QMeAWMuRsGntFs0+38nQMh6Ebiev/OOeggMD4=@vger.kernel.org X-Gm-Message-State: AOJu0Yx19YfMUymtBXRL1OyLMwA1d8UoViZP9mWLoMowqKuXt7CzilHb 8D5K9kotRva2necJ8hqUWxFTdETlJWy0CN4831XB1qnsrDNd8LPJARgZpDhdCZ55CIXqb9BFHkY 7V69LI/y66zC++kVklXwuCazr2DRp7Nxz7OnhC7Xygi/aPCVHwT8hOPjuVBw= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:211:b0:696:8278:c619 with SMTP id 006d021491bc7-696979ad7d2mr2963413eaf.6.1777813300089; Sun, 03 May 2026 06:01:40 -0700 (PDT) Date: Sun, 03 May 2026 06:01:40 -0700 In-Reply-To: <69f44505.050a0220.3cbe47.0008.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69f74734.050a0220.312cd3.0033.GAE@google.com> Subject: Re: [syzbot] [mptcp?] KMSAN: uninit-value in mptcp_established_options From: syzbot To: davem@davemloft.net, edumazet@google.com, geliang@kernel.org, horms@kernel.org, kmta1236@gmail.com, kuba@kernel.org, kuni1840@gmail.com, kuniyu@google.com, linux-kernel@vger.kernel.org, martineau@kernel.org, matttbe@kernel.org, mptcp@lists.linux.dev, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 66edb901bf87 Merge tag 'v7.1-p3' of git://git.kernel.org/p.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1086da36580000 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 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1260fece580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/9014c04fc561/disk-66edb901.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/a96b1e11a924/vmlinux-66edb901.xz kernel image: https://storage.googleapis.com/syzbot-assets/680236de6331/bzImage-66edb901.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+ff020673c5e3d94d9478@syzkaller.appspotmail.com ===================================================== BUG: KMSAN: uninit-value in mptcp_write_data_fin net/mptcp/options.c:542 [inline] BUG: KMSAN: uninit-value in mptcp_established_options_dss net/mptcp/options.c:590 [inline] BUG: KMSAN: uninit-value in mptcp_established_options+0x112f/0x3530 net/mptcp/options.c:874 mptcp_write_data_fin net/mptcp/options.c:542 [inline] mptcp_established_options_dss net/mptcp/options.c:590 [inline] mptcp_established_options+0x112f/0x3530 net/mptcp/options.c:874 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_shutdown+0x164/0x690 net/mptcp/protocol.c:3137 mptcp_check_send_data_fin+0x31b/0x3d0 net/mptcp/protocol.c:3218 __mptcp_wr_shutdown net/mptcp/protocol.c:3234 [inline] __mptcp_close+0x860/0x1360 net/mptcp/protocol.c:3313 mptcp_close+0x42/0x260 net/mptcp/protocol.c:3367 inet_release+0x1ee/0x2a0 net/ipv4/af_inet.c:442 __sock_release net/socket.c:722 [inline] sock_close+0xd6/0x2f0 net/socket.c:1514 __fput+0x60e/0x1010 fs/file_table.c:510 ____fput+0x25/0x30 fs/file_table.c:538 task_work_run+0x208/0x2b0 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:67 [inline] exit_to_user_mode_loop+0x306/0x1b60 kernel/entry/common.c:98 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x236/0xf80 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f 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: 5905 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 ===================================================== --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.