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 DF3382F87B; Fri, 8 May 2026 10:46:41 +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=1778237202; cv=none; b=uz1pyI3aGOvAembJ/ZWTSkTKxmUfbBP4ng4PSw622J01M5lDjkOcH5lUi+3SlJnloPNyNrVVuId2pZWB46EDDxhLZj6rFtHaoemlwPjSL0qPJjw4bmvqJzAXc3tcPfMZ82CvpLEC3cVU3/SnZxN5AthAek5yCppo5RLCxq/A3qU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778237202; c=relaxed/simple; bh=xf6BGLSfRGHCKfcnkN3d0PQtyTozP0RjLq6vHzEGdiY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=if/mN7QnbdvtFscnlUQalPkw0yaNkAwXPp3KgoElPVgl9JCC+SPQ5jwwjTQbwpefPhT8QFEuhBqLHkkrioA3ZEeLWcuLvsmxgFhnRmjt2sxFVVwF5N3Uh/En8vre5rsrWncGrYiNj3Ud5PgKQmFnxAKfky56zLYU4QP+LLe80yo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NXojbh09; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NXojbh09" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF89FC2BCB0; Fri, 8 May 2026 10:46:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778237201; bh=xf6BGLSfRGHCKfcnkN3d0PQtyTozP0RjLq6vHzEGdiY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=NXojbh09MBN0F00EIlOJ7aNjEaicIcQ4nUbOEJzpMiblzunAcWr0c8RtpMOG+uXPh qXH7DGZD1xCGMUysWVkC2X8iWf0s4yqWNepZGYcZd3MlOgA+abtOS9327IzRidpOin dBsJZequpdXOmJiuJRu1RnWjANDl0mzaluk33cuZpHiLGHTEhONH0nQgGSOEMdGLzT IGKqI6W3S7r8wjVe0JueLP5L2wmZ5nCg0lDL/Bt1spMuE3wmXRTNm8cCStDb4p8TGw ov4HVJL6YARcw3moivN8V2JMnPk8eYTxU05ctUabYlbQTP4N65+ohgdm/imr/SmeIK GSMqUwYeagj5A== Message-ID: <43a84c8c-0d65-400e-b735-76210af4cddb@kernel.org> Date: Fri, 8 May 2026 12:46:36 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [syzbot] [mptcp?] KMSAN: uninit-value in mptcp_established_options Content-Language: fr To: Alexander Potapenko , Paolo Abeni Cc: kuniyu@google.com, syzbot , linux-kernel@vger.kernel.org, mptcp@lists.linux.dev, syzkaller-bugs@googlegroups.com References: <69f8e352.170a0220.bb392.0005.GAE@google.com> <2a9bde65-d2de-44cc-9192-e7aa8a0935a7@kernel.org> <672f5b7d-6fa0-41c5-a950-2890028c8572@redhat.com> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Alexander, Thank you for your reply! On 08/05/2026 12:11, Alexander Potapenko wrote: > On Fri, May 8, 2026 at 11:27 AM 'Paolo Abeni' via syzkaller-bugs > wrote: >> >> On 5/7/26 9:44 AM, Matthieu Baerts wrote: >>> Hi Paolo, Kuniyuki, >>> >>> On 04/05/2026 20:20, syzbot wrote: >>>> Hello, >>>> >>>> syzbot has tested the proposed patch but the reproducer is still triggering an issue: >>>> KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt >>> >>> It looks like the issue is different now: >>> >>>> ===================================================== >>>> BUG: KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt+0xb0/0xc0 include/linux/irq-entry-common.h:472 >>>> irqentry_exit_to_kernel_mode_preempt+0xb0/0xc0 include/linux/irq-entry-common.h:472 >>>> irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline] >>>> irqentry_exit+0x7b/0x760 kernel/entry/common.c:164 >>>> sysvec_apic_timer_interrupt+0x52/0x90 arch/x86/kernel/apic/apic.c:1061 >>>> asm_sysvec_apic_timer_interrupt+0x1f/0x30 arch/x86/include/asm/idtentry.h:697 >>>> kmsan_get_metadata+0x17/0x160 mm/kmsan/shadow.c:125 >>>> kmsan_get_shadow_origin_ptr+0x4a/0xb0 mm/kmsan/shadow.c:102 >>>> get_shadow_origin_ptr mm/kmsan/instrumentation.c:38 [inline] >>>> __msan_metadata_ptr_for_load_4+0x24/0x40 mm/kmsan/instrumentation.c:93 >>>> tcp_data_queue+0xdc/0x7c90 net/ipv4/tcp_input.c:5589 >>>> tcp_rcv_established+0x19bb/0x3200 net/ipv4/tcp_input.c:6656 >>>> tcp_v4_do_rcv+0xc4b/0x1b10 net/ipv4/tcp_ipv4.c:1852 >>>> sk_backlog_rcv include/net/sock.h:1190 [inline] >>> >>> That's the input side. >>> >>>> __release_sock+0x360/0x7d0 net/core/sock.c:3216 >>>> release_sock+0x22d/0x300 net/core/sock.c:3815 >>>> mptcp_subflow_shutdown+0x358/0x690 net/mptcp/protocol.c:3144 >>>> 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 mp_opt created at: >>>> mptcp_incoming_options+0x11d/0x43b0 net/mptcp/options.c:1171 >>> >>> Confirmed here. With "struct mptcp_options_received" while the original >>> issue was with "struct mptcp_out_options". >>> >>> Plus I'm not exactly sure to understand the issue here: mp_opt is >>> defined and used only in mptcp_incoming_options(), and I don't see >>> anything using it after the end of this function. Or did I miss something? >> >> I also had hard time understanding the backtrace, I think some frames >> are omitted/missing (it happens sometime, IDK why), specifically the one >> related to mptcp_options_received() - which would be useful to >> understand the issue. > > This is probably related to > https://lore.kernel.org/all/69e7ee1f.a00a0220.17a17.001d.GAE@google.com/T/ Ah yes, it looks similar. > Let me send the patch, perhaps this issue will also go away. That would be great, thank you! Cheers, Matt -- Sponsored by the NGI0 Core fund.