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AHgh+RqfK9/JKo04uLG5PjXbkqj5s/2BJ+ykdV2ihdErtmnLhH7lSEFLGjqd6stBsmr/q1iMFl6VOT7TLIA=@vger.kernel.org X-Gm-Message-State: AOJu0YxDTBUUsd4cUqSqppCZ/dFtaAEEtyaN6LkvpVHIsay3fV+1pyfv pqjDMYY42jTkH/fUySanMFXdNuuggnQQjBrteDBHcJ1ArHD5+deWKwMfkwTZfzvHVsYOfb/16qC G2YbTaWWLJkHNt6JgDliFYxgEYRSM8IrVtt0FFnaV2CB4n7OC1CLzcysIShk= Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:4fe8:b0:4a4:adaf:5570 with SMTP id 5614622812f47-4af5dfb3ddcmr1716623b6e.4.1785518130422; Fri, 31 Jul 2026 10:15:30 -0700 (PDT) Date: Fri, 31 Jul 2026 10:15:30 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a6cd832.1aa927e4.17d4bf.0007.GAE@google.com> Subject: [syzbot] [usb?] possible deadlock in digi_set_modem_signals From: syzbot To: gregkh@linuxfoundation.org, johan@kernel.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 11028ab62899 Merge tag 'probes-fixes-v7.2-rc5' of git://gi.. git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=13574aea580000 kernel config: https://syzkaller.appspot.com/x/.config?x=cb17729fb04b1e3a dashboard link: https://syzkaller.appspot.com/bug?extid=2051460e19471eeb42c3 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16643632580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1535b03e580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/0afad3dd27f4/disk-11028ab6.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/2e1441f9c31d/vmlinux-11028ab6.xz kernel image: https://storage.googleapis.com/syzbot-assets/5f0b8bdf00cd/bzImage-11028ab6.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+2051460e19471eeb42c3@syzkaller.appspotmail.com ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz-executor164/5616 is trying to acquire lock: ffff888037675858 (&priv->dp_port_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] ffff888037675858 (&priv->dp_port_lock){+.+.}-{3:3}, at: digi_set_modem_signals+0x19d/0x8c0 drivers/usb/serial/digi_acceleport.c:525 but task is already holding lock: ffff888037676058 (&priv->dp_port_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] ffff888037676058 (&priv->dp_port_lock){+.+.}-{3:3}, at: digi_set_modem_signals+0x195/0x8c0 drivers/usb/serial/digi_acceleport.c:524 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&priv->dp_port_lock); lock(&priv->dp_port_lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor164/5616: #0: ffff8880379d71a0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev+0x74/0x4d0 drivers/tty/tty_io.c:1406 #1: ffff888037676058 (&priv->dp_port_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline] #1: ffff888037676058 (&priv->dp_port_lock){+.+.}-{3:3}, at: digi_set_modem_signals+0x195/0x8c0 drivers/usb/serial/digi_acceleport.c:524 #2: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #2: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #2: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: __rt_spin_lock kernel/locking/spinlock_rt.c:50 [inline] #2: ffffffff8e1c3000 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1e0/0x400 kernel/locking/spinlock_rt.c:57 stack backtrace: CPU: 0 UID: 0 PID: 5616 Comm: syz-executor164 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x24df/0x2ce0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56 spin_lock include/linux/spinlock_rt.h:45 [inline] digi_set_modem_signals+0x19d/0x8c0 drivers/usb/serial/digi_acceleport.c:525 tty_port_raise_dtr_rts drivers/tty/tty_port.c:456 [inline] tty_port_block_til_ready+0x386/0x890 drivers/tty/tty_port.c:540 tty_open+0x496/0xcd0 drivers/tty/tty_io.c:2137 chrdev_open+0x4dc/0x600 fs/char_dev.c:411 do_dentry_open+0x849/0x1420 fs/open.c:947 vfs_open+0x3b/0x350 fs/open.c:1052 do_open fs/namei.c:4700 [inline] path_openat+0x2e60/0x3850 fs/namei.c:4863 do_file_open+0x23e/0x4a0 fs/namei.c:4892 do_sys_openat2+0x115/0x200 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2dafacdfc9 Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 d8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe4d880a08 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 0000200000000400 RCX: 00007f2dafacdfc9 RDX: 000000000000e002 RSI: 0000200000000400 RDI: 00000000ffffff9c RBP: 0000200000000408 R08: 0000000000000006 R09: 0000000000000006 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe4d880b78 R13: 431bde82d7b634db R14: 00007f2dafb61c40 R15: 0000000000000002 --- 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