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 9D362246BC5; Mon, 23 Feb 2026 13:40:18 +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=1771854018; cv=none; b=ZxJFDCn6jr9/+wYK0KNLWx7QKe/04fShi9/2i74F77WD7JWk7DznGMtbZypcUwwCH+HNl82HtgUwYWinbwcaWoPhRzDaFSg4n5IOOi3Zq+62tjCX6MvUNFHrZo2xAm6hcSA/72d8RY+UndXMzw5L36cCZKaQ7mmYVIhZGF08ZzU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771854018; c=relaxed/simple; bh=iZ0XcCxmBBYH6KpAWY4sREAqUKNfN0e39tteAnfrA+w=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qwIDOZZk7FPSpUeQVv6RnSDsXxkVDkBi1nzHFS2bJDl+cISmUhfN9zDfYUZCVGbCCAZFW1jiXNYnjZvi7GjC560Gmpc/0nLPNqXzw8ckUbkCNTH3xUm8Cx2a/YZlZu2sz6j6NkqlM3vQdNcRzRYTiV0BhJTT2o73XYDiIcA254Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eJIXAFPq; 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="eJIXAFPq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D912EC116C6; Mon, 23 Feb 2026 13:40:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771854018; bh=iZ0XcCxmBBYH6KpAWY4sREAqUKNfN0e39tteAnfrA+w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eJIXAFPqZn9O0pN4rWKorOweIL99L2YBIN377oG3v9wlSu+5Ud5UWz8fIOSv+rVRK jLOTfdGd1yIVxcfy/XYOG1kYgFLjo2o6aBt31uTbX6/N9+zmbbOF0LmNn8swVZf8MI Vk25e1cMBrl49+31G5xBBW49DXCjyWRSGs14pukGExk1C6IC9qmaksPrbf6HEfTNvp B4wkwjOkP1dD4/QdU0wkSRoRib6xxiTqwp9mJxaZT5HPNCiiPPjdrEsM8zQh+Rn55H 3ixbwj41FXqbBcsg7R0RgqXCsunez2gpYjGhXHK0kZLNi3jcHo/DGLT2Ya15rfpQ+g 1CNTLmFI+PwMw== Date: Mon, 23 Feb 2026 14:40:15 +0100 From: Frederic Weisbecker To: syzbot , =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= , =?iso-8859-1?Q?G=FCnther?= Noack , Paul Moore , James Morris , "Serge E. Hallyn" , linux-security-module@vger.kernel.org Cc: anna-maria@linutronix.de, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tglx@kernel.org Subject: Re: [syzbot] [kernel?] INFO: task hung in restrict_one_thread_callback Message-ID: References: <69984159.050a0220.21cd75.01bb.GAE@google.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <69984159.050a0220.21cd75.01bb.GAE@google.com> Le Fri, Feb 20, 2026 at 03:11:21AM -0800, syzbot a écrit : > Hello, > > syzbot found the following issue on: > > HEAD commit: 635c467cc14e Add linux-next specific files for 20260213 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=1452f6e6580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=61690c38d1398936 > dashboard link: https://syzkaller.appspot.com/bug?extid=7ea2f5e9dfd468201817 > 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=16e41c02580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15813652580000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/78b3d15ca8e6/disk-635c467c.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/a95f3d108ef4/vmlinux-635c467c.xz > kernel image: https://storage.googleapis.com/syzbot-assets/e58086838b24/bzImage-635c467c.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+7ea2f5e9dfd468201817@syzkaller.appspotmail.com > > INFO: task syz.0.2812:14643 blocked for more than 143 seconds. > Not tainted syzkaller #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:syz.0.2812 state:D stack:25600 pid:14643 tgid:14643 ppid:13375 task_flags:0x400040 flags:0x00080002 > Call Trace: > > context_switch kernel/sched/core.c:5295 [inline] > __schedule+0x1585/0x5340 kernel/sched/core.c:6907 > __schedule_loop kernel/sched/core.c:6989 [inline] > schedule+0x164/0x360 kernel/sched/core.c:7004 > schedule_timeout+0xc3/0x2c0 kernel/time/sleep_timeout.c:75 > do_wait_for_common kernel/sched/completion.c:100 [inline] > __wait_for_common kernel/sched/completion.c:121 [inline] > wait_for_common kernel/sched/completion.c:132 [inline] > wait_for_completion+0x2cc/0x5e0 kernel/sched/completion.c:153 > restrict_one_thread security/landlock/tsync.c:128 [inline] > restrict_one_thread_callback+0x320/0x570 security/landlock/tsync.c:162 Seems to be related to landlock security module. Cc'ing maintainers for awareness. Thanks. > task_work_run+0x1d9/0x270 kernel/task_work.c:233 > get_signal+0x11eb/0x1330 kernel/signal.c:2807 > arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337 > __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] > exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98 > __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] > syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] > syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] > do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f8d7f19bf79 > RSP: 002b:00007ffe0b192a38 EFLAGS: 00000246 ORIG_RAX: 00000000000000db > RAX: fffffffffffffdfc RBX: 00000000000389f1 RCX: 00007f8d7f19bf79 > RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f8d7f41618c > RBP: 0000000000000032 R08: 3fffffffffffffff R09: 0000000000000000 > R10: 00007ffe0b192b40 R11: 0000000000000246 R12: 00007ffe0b192b60 > R13: 00007f8d7f41618c R14: 0000000000038a23 R15: 00007ffe0b192b40 > > INFO: task syz.0.2812:14644 blocked for more than 143 seconds. > Not tainted syzkaller #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:syz.0.2812 state:D stack:28216 pid:14644 tgid:14643 ppid:13375 task_flags:0x400040 flags:0x00080002 > Call Trace: > > context_switch kernel/sched/core.c:5295 [inline] > __schedule+0x1585/0x5340 kernel/sched/core.c:6907 > __schedule_loop kernel/sched/core.c:6989 [inline] > schedule+0x164/0x360 kernel/sched/core.c:7004 > schedule_timeout+0xc3/0x2c0 kernel/time/sleep_timeout.c:75 > do_wait_for_common kernel/sched/completion.c:100 [inline] > __wait_for_common kernel/sched/completion.c:121 [inline] > wait_for_common kernel/sched/completion.c:132 [inline] > wait_for_completion+0x2cc/0x5e0 kernel/sched/completion.c:153 > restrict_one_thread security/landlock/tsync.c:128 [inline] > restrict_one_thread_callback+0x320/0x570 security/landlock/tsync.c:162 > task_work_run+0x1d9/0x270 kernel/task_work.c:233 > get_signal+0x11eb/0x1330 kernel/signal.c:2807 > arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337 > __exit_to_user_mode_loop kernel/entry/common.c:64 [inline] > exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98 > __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] > syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] > syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline] > do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f8d7f19bf79 > RSP: 002b:00007f8d8007c0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca > RAX: fffffffffffffe00 RBX: 00007f8d7f415fa8 RCX: 00007f8d7f19bf79 > RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f8d7f415fa8 > RBP: 00007f8d7f415fa0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007f8d7f416038 R14: 00007ffe0b1927f0 R15: 00007ffe0b1928d8 > > INFO: task syz.0.2812:14645 blocked for more than 143 seconds. > Not tainted syzkaller #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:syz.0.2812 state:D stack:28648 pid:14645 tgid:14643 ppid:13375 task_flags:0x400140 flags:0x00080006 > Call Trace: > > context_switch kernel/sched/core.c:5295 [inline] > __schedule+0x1585/0x5340 kernel/sched/core.c:6907 > __schedule_loop kernel/sched/core.c:6989 [inline] > schedule+0x164/0x360 kernel/sched/core.c:7004 > schedule_timeout+0xc3/0x2c0 kernel/time/sleep_timeout.c:75 > do_wait_for_common kernel/sched/completion.c:100 [inline] > __wait_for_common kernel/sched/completion.c:121 [inline] > wait_for_common kernel/sched/completion.c:132 [inline] > wait_for_completion+0x2cc/0x5e0 kernel/sched/completion.c:153 > landlock_restrict_sibling_threads+0xe9c/0x11f0 security/landlock/tsync.c:539 > __do_sys_landlock_restrict_self security/landlock/syscalls.c:574 [inline] > __se_sys_landlock_restrict_self+0x540/0x810 security/landlock/syscalls.c:482 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f8d7f19bf79 > RSP: 002b:00007f8d8005b028 EFLAGS: 00000246 ORIG_RAX: 00000000000001be > RAX: ffffffffffffffda RBX: 00007f8d7f416090 RCX: 00007f8d7f19bf79 > RDX: 0000000000000000 RSI: 000000000000000e RDI: 0000000000000003 > RBP: 00007f8d7f2327e0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007f8d7f416128 R14: 00007f8d7f416090 R15: 00007ffe0b1928d8 > > INFO: task syz.0.2812:14646 blocked for more than 144 seconds. > Not tainted syzkaller #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:syz.0.2812 state:D stack:28832 pid:14646 tgid:14643 ppid:13375 task_flags:0x400140 flags:0x00080006 > Call Trace: > > context_switch kernel/sched/core.c:5295 [inline] > __schedule+0x1585/0x5340 kernel/sched/core.c:6907 > __schedule_loop kernel/sched/core.c:6989 [inline] > schedule+0x164/0x360 kernel/sched/core.c:7004 > schedule_timeout+0xc3/0x2c0 kernel/time/sleep_timeout.c:75 > do_wait_for_common kernel/sched/completion.c:100 [inline] > __wait_for_common kernel/sched/completion.c:121 [inline] > wait_for_common kernel/sched/completion.c:132 [inline] > wait_for_completion+0x2cc/0x5e0 kernel/sched/completion.c:153 > landlock_restrict_sibling_threads+0xe9c/0x11f0 security/landlock/tsync.c:539 > __do_sys_landlock_restrict_self security/landlock/syscalls.c:574 [inline] > __se_sys_landlock_restrict_self+0x540/0x810 security/landlock/syscalls.c:482 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f8d7f19bf79 > RSP: 002b:00007f8d8003a028 EFLAGS: 00000246 ORIG_RAX: 00000000000001be > RAX: ffffffffffffffda RBX: 00007f8d7f416180 RCX: 00007f8d7f19bf79 > RDX: 0000000000000000 RSI: 000000000000000e RDI: 0000000000000003 > RBP: 00007f8d7f2327e0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 00007f8d7f416218 R14: 00007f8d7f416180 R15: 00007ffe0b1928d8 > > > Showing all locks held in the system: > 1 lock held by khungtaskd/31: > #0: ffffffff8e9602e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline] > #0: ffffffff8e9602e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline] > #0: ffffffff8e9602e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775 > 2 locks held by getty/5581: > #0: ffff8880328890a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 > #1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0 drivers/tty/n_tty.c:2211 > > ============================================= > > NMI backtrace for cpu 0 > CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 > Call Trace: > > dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 > nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113 > nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62 > trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline] > __sys_info lib/sys_info.c:157 [inline] > sys_info+0x135/0x170 lib/sys_info.c:165 > check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline] > watchdog+0xfd9/0x1030 kernel/hung_task.c:515 > kthread+0x388/0x470 kernel/kthread.c:467 > ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > Sending NMI from CPU 0 to CPUs 1: > NMI backtrace for cpu 1 > CPU: 1 UID: 0 PID: 86 Comm: kworker/u8:5 Not tainted syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 > Workqueue: events_unbound nsim_dev_trap_report_work > RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:26 [inline] > RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline] > RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:127 [inline] > RIP: 0010:lock_acquire+0xab/0x2e0 kernel/locking/lockdep.c:5864 > Code: 84 c1 00 00 00 65 8b 05 73 b8 9f 11 85 c0 0f 85 b2 00 00 00 65 48 8b 05 bb 72 9f 11 83 b8 14 0b 00 00 00 0f 85 9d 00 00 00 9c <5b> fa 48 c7 c7 8f a1 02 8e e8 57 40 17 0a 65 ff 05 40 b8 9f 11 45 > RSP: 0018:ffffc9000260f498 EFLAGS: 00000246 > RAX: ffff88801df81e40 RBX: ffffffff818f9166 RCX: 0000000080000002 > RDX: 0000000000000000 RSI: ffffffff8176da62 RDI: 1ffffffff1d2c05c > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: ffffc9000260f638 R11: ffffffff81b11580 R12: 0000000000000002 > R13: ffffffff8e9602e0 R14: 0000000000000000 R15: 0000000000000000 > FS: 0000000000000000(0000) GS:ffff88812510b000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fe09b2c1ff8 CR3: 000000000e74c000 CR4: 00000000003526f0 > Call Trace: > > rcu_lock_acquire include/linux/rcupdate.h:312 [inline] > rcu_read_lock include/linux/rcupdate.h:850 [inline] > class_rcu_constructor include/linux/rcupdate.h:1193 [inline] > unwind_next_frame+0xc2/0x23c0 arch/x86/kernel/unwind_orc.c:495 > arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 > stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 > kasan_save_stack mm/kasan/common.c:57 [inline] > kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 > unpoison_slab_object mm/kasan/common.c:340 [inline] > __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 > kasan_slab_alloc include/linux/kasan.h:253 [inline] > slab_post_alloc_hook mm/slub.c:4501 [inline] > slab_alloc_node mm/slub.c:4830 [inline] > kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4882 > __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702 > alloc_skb include/linux/skbuff.h:1383 [inline] > nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:819 [inline] > nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline] > nsim_dev_trap_report_work+0x29a/0xb80 drivers/net/netdevsim/dev.c:922 > process_one_work+0x949/0x1650 kernel/workqueue.c:3279 > process_scheduled_works kernel/workqueue.c:3362 [inline] > worker_thread+0xb46/0x1140 kernel/workqueue.c:3443 > kthread+0x388/0x470 kernel/kthread.c:467 > ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > > > --- > 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 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. > > 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 -- Frederic Weisbecker SUSE Labs