syzbot has found a reproducer for the following issue on: HEAD commit: 595523945be0 Merge tag 'devicetree-fixes-for-6.13-2' of gi.. git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=124d7a18580000 kernel config: https://syzkaller.appspot.com/x/.config?x=d1cb4a1f148c0861 dashboard link: https://syzkaller.appspot.com/bug?extid=52cf91760dcb1dac6376 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=164091f8580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17903fc4580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/6f7863c08b5c/disk-59552394.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/06971b2686d0/vmlinux-59552394.xz kernel image: https://storage.googleapis.com/syzbot-assets/66c751022d90/bzImage-59552394.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+52cf91760dcb1dac6376@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.13.0-rc7-syzkaller-00189-g595523945be0 #0 Not tainted ------------------------------------------------------ kworker/1:4/5864 is trying to acquire lock: ffff88801b0990b8 (&buf->lock){+.+.}-{4:4}, at: tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:229 but task is already holding lock: ffffffff8e1a9040 (console_lock){+.+.}-{0:0}, at: vc_SAK+0x13/0x310 drivers/tty/vt/vt_ioctl.c:983 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (console_lock){+.+.}-{0:0}: console_lock+0x7a/0xa0 kernel/printk/printk.c:2833 con_flush_chars+0x5e/0x80 drivers/tty/vt/vt.c:3503 __receive_buf drivers/tty/n_tty.c:1644 [inline] n_tty_receive_buf_common+0xa99/0x1980 drivers/tty/n_tty.c:1739 tty_ldisc_receive_buf+0xa2/0x190 drivers/tty/tty_buffer.c:387 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x264/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3317 [inline] worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #1 (&tty->termios_rwsem){++++}-{4:4}: down_read+0x9a/0x330 kernel/locking/rwsem.c:1524 n_tty_receive_buf_common+0x85/0x1980 drivers/tty/n_tty.c:1702 tty_ldisc_receive_buf+0xa2/0x190 drivers/tty/tty_buffer.c:387 tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37 receive_buf drivers/tty/tty_buffer.c:445 [inline] flush_to_ldisc+0x264/0x780 drivers/tty/tty_buffer.c:495 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3317 [inline] worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #0 (&buf->lock){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:229 tty_ldisc_flush+0x64/0xe0 drivers/tty/tty_ldisc.c:388 __do_SAK+0x6a1/0x800 drivers/tty/tty_io.c:3038 vc_SAK+0x7f/0x310 drivers/tty/vt/vt_ioctl.c:993 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3317 [inline] worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Chain exists of: &buf->lock --> &tty->termios_rwsem --> console_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(console_lock); lock(&tty->termios_rwsem); lock(console_lock); lock(&buf->lock); *** DEADLOCK *** 4 locks held by kworker/1:4/5864: #0: ffff88801b078948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1293/0x1ba0 kernel/workqueue.c:3211 #1: ffffc90004a9fd80 ((work_completion)(&vc_cons[currcons].SAK_work)){+.+.}-{0:0}, at: process_one_work+0x921/0x1ba0 kernel/workqueue.c:3212 #2: ffffffff8e1a9040 (console_lock){+.+.}-{0:0}, at: vc_SAK+0x13/0x310 drivers/tty/vt/vt_ioctl.c:983 #3: ffff8880698950a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref drivers/tty/tty_ldisc.c:263 [inline] #3: ffff8880698950a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_flush+0x1c/0xe0 drivers/tty/tty_ldisc.c:386 stack backtrace: CPU: 1 UID: 0 PID: 5864 Comm: kworker/1:4 Not tainted 6.13.0-rc7-syzkaller-00189-g595523945be0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 Workqueue: events vc_SAK Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206 check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xa60 kernel/locking/mutex.c:735 tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:229 tty_ldisc_flush+0x64/0xe0 drivers/tty/tty_ldisc.c:388 __do_SAK+0x6a1/0x800 drivers/tty/tty_io.c:3038 vc_SAK+0x7f/0x310 drivers/tty/vt/vt_ioctl.c:993 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3317 [inline] worker_thread+0x6c8/0xf00 kernel/workqueue.c:3398 kthread+0x2c1/0x3a0 kernel/kthread.c:389 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 </TASK> tty tty1: SAK: killed process 5889 (syz-executor496): by fd#4 usb 2-1: USB disconnect, device number 3 usb 2-1: new high-speed USB device number 4 using dummy_hcd usb 2-1: config 0 interface 0 altsetting 0 endpoint 0x81 has an invalid bInterval 0, changing to 7 usb 2-1: New USB device found, idVendor=0926, idProduct=3333, bcdDevice= 0.40 usb 2-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0 usb 2-1: config 0 descriptor?? keytouch 0003:0926:3333.000F: fixing up Keytouch IEC report descriptor input: HID 0926:3333 as /devices/platform/dummy_hcd.1/usb2/2-1/2-1:0.0/0003:0926:3333.000F/input/input19 keytouch 0003:0926:3333.000F: input,hidraw2: USB HID v0.00 Keyboard [HID 0926:3333] on usb-dummy_hcd.1-1/input0 --- 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.
