From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f80.google.com (mail-oo1-f80.google.com [209.85.161.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 007503BBA05 for ; Tue, 14 Apr 2026 09:14:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.80 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776158073; cv=none; b=kqzjen1R7rs+TB3LCqljLyrfedDVqR73rZ7sGYWhNERUgGg1N0B+TBn6RgPdIGSNabs4SvMcNTZzri/jDpHRlzl7wpYDNBG2WBAx18uRFdXZOPA35y+2LEpmUcFJt4LAHFhDWHXoQJrG6DuE4c6Ae/aACSevyyvg7Wtx/dis/DQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776158073; c=relaxed/simple; bh=GPNEvwTV3YCZM/IQhX2qX/16wfmzdwPlkAEZNY2yz18=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=MqBpVVTtOIwuKzdMk4MKoCbPoSEdcIqNHmQO98gMuLI1wl9vb42xniUnHEZFH2ZCkb514FJ0GJaSNTXannMU4QU8AoxuJfDAOf17GEdZUidQwizv1+Ws5ndwKqW8WMMrYit78cctOQdQJ+RrOZu/bX6Bhc3wHvSL/8iiSYbt07g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.161.80 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oo1-f80.google.com with SMTP id 006d021491bc7-66b612efb4aso8574036eaf.0 for ; Tue, 14 Apr 2026 02:14:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776158070; x=1776762870; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=c4/P5vYiyQeQxekanU/M1VkImZhr/JuEMOleJPaKHW0=; b=KkIQsSKhaUOy9UKe3BCoOmqzDx/bVaVMTElQ66w8FA5C6kRr9ZPEFyamWcAH8L9t4F Vq9wtKgFDh46D6SX83wZlc/DoppUab7VsJ3jf/OD+h6k6/w1mVd7PJHllAZe613R5psH EwVAvLJaQuwdjQVUePFk84NpuOmNzX5lWIBnCtg00Z3cRBAakMOqvsPbpOf+3fl8OD/b MNJljSL9ZIGNw8tkqRgUu5V8Tb6vzcz5suft8r4UPPtGdC1Ax6fNy/cfrImMFhb/YJYc SEfXZo2MzfSTPtdvaz3DYT35Xi0O8hITxcSSmHiTtQIQI1p7dF0Qytpcmb66MvltQa2s EA9w== X-Forwarded-Encrypted: i=1; AFNElJ9P35uil6oQHHAhgTRGVjhIHLEe7Ens7RadQ86zr9IJxRtgARD1TeAwEYnyGt9F7h4YD0GFzuvlEMRXrPs=@vger.kernel.org X-Gm-Message-State: AOJu0Yx3k3xjw8pYXUPcGf6tPCP2oD5XEeakGYrpTF+y+7CfpD9CVJyu uviBxU3AGX7m3Ta0UAjpFUu3SYbwWmkvDLR9qBamCrwEV6wDKEUs1ikR8+iJAVTEmmBJqs7CicI y+pvJigna+xIdJ0qRZBstb/GbIiQrJ6Lv/fEM8nXr0b5ot6d3LBSYV1k/5zc= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:628d:b0:683:a6e:970a with SMTP id 006d021491bc7-68a6b54c90cmr7115601eaf.40.1776158069823; Tue, 14 Apr 2026 02:14:29 -0700 (PDT) Date: Tue, 14 Apr 2026 02:14:29 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69de0575.a00a0220.468cb.005c.GAE@google.com> Subject: [syzbot] [ppp?] KMSAN: uninit-value in ppp_sync_receive (4) From: syzbot To: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-ppp@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 9a9c8ce300cd Merge tag 'kbuild-fixes-7.0-4' of git://git.k.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=112a874e580000 kernel config: https://syzkaller.appspot.com/x/.config?x=963de479f54c6dbb dashboard link: https://syzkaller.appspot.com/bug?extid=88679c919eb801bd16f8 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/3e2ad23d804a/disk-9a9c8ce3.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/a3dde4990296/vmlinux-9a9c8ce3.xz kernel image: https://storage.googleapis.com/syzbot-assets/256e0a89d22c/bzImage-9a9c8ce3.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+88679c919eb801bd16f8@syzkaller.appspotmail.com ===================================================== BUG: KMSAN: uninit-value in ppp_sync_input drivers/net/ppp/ppp_synctty.c:684 [inline] BUG: KMSAN: uninit-value in ppp_sync_receive+0x626/0xfa0 drivers/net/ppp/ppp_synctty.c:334 ppp_sync_input drivers/net/ppp/ppp_synctty.c:684 [inline] ppp_sync_receive+0x626/0xfa0 drivers/net/ppp/ppp_synctty.c:334 tty_ldisc_receive_buf+0x1f7/0x2c0 drivers/tty/tty_buffer.c:391 tty_port_default_receive_buf+0xd7/0x1a0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x43e/0xe40 drivers/tty/tty_buffer.c:495 process_one_work kernel/workqueue.c:3276 [inline] process_scheduled_works+0xb82/0x1e80 kernel/workqueue.c:3359 worker_thread+0xee4/0x1590 kernel/workqueue.c:3440 kthread+0x53f/0x600 kernel/kthread.c:436 ret_from_fork+0x20f/0x910 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Uninit was created at: slab_post_alloc_hook mm/slub.c:4545 [inline] slab_alloc_node mm/slub.c:4866 [inline] __do_kmalloc_node mm/slub.c:5259 [inline] __kmalloc_noprof+0x486/0x1680 mm/slub.c:5272 kmalloc_noprof include/linux/slab.h:954 [inline] tty_buffer_alloc drivers/tty/tty_buffer.c:180 [inline] __tty_buffer_request_room+0x3d4/0x7a0 drivers/tty/tty_buffer.c:273 __tty_insert_flip_string_flags+0x157/0x6e0 drivers/tty/tty_buffer.c:309 tty_insert_flip_char include/linux/tty_flip.h:77 [inline] uart_insert_char+0x368/0x930 drivers/tty/serial/serial_core.c:3431 serial8250_read_char+0x1ba/0x670 drivers/tty/serial/8250/8250_port.c:1643 serial8250_rx_chars drivers/tty/serial/8250/8250_port.c:1660 [inline] serial8250_handle_irq_locked+0x6d4/0xa40 drivers/tty/serial/8250/8250_port.c:1820 serial8250_handle_irq+0x187/0x730 drivers/tty/serial/8250/8250_port.c:1841 serial8250_default_handle_irq+0x116/0x370 drivers/tty/serial/8250/8250_port.c:1855 serial8250_interrupt+0xcb/0x420 drivers/tty/serial/8250/8250_core.c:86 __handle_irq_event_percpu+0x13c/0xf90 kernel/irq/handle.c:209 handle_irq_event_percpu kernel/irq/handle.c:246 [inline] handle_irq_event+0xe0/0x2a0 kernel/irq/handle.c:263 handle_edge_irq+0x2a9/0xb30 kernel/irq/chip.c:855 generic_handle_irq_desc include/linux/irqdesc.h:186 [inline] handle_irq arch/x86/kernel/irq.c:262 [inline] call_irq_handler arch/x86/kernel/irq.c:-1 [inline] __common_interrupt+0x9d/0x180 arch/x86/kernel/irq.c:333 common_interrupt+0x4c/0xb0 arch/x86/kernel/irq.c:326 asm_common_interrupt+0x2b/0x40 arch/x86/include/asm/idtentry.h:688 CPU: 0 UID: 0 PID: 35 Comm: kworker/u8:2 Tainted: G W L syzkaller #0 PREEMPT(full) Tainted: [W]=WARN, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Workqueue: events_unbound flush_to_ldisc ===================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup