Extracting prog: 1m11.098822861s
Minimizing prog: 9m45.621864747s
Simplifying prog options: 0s
Extracting C: 23.327340417s
Simplifying C: 4m18.739533826s


extracting reproducer from 1 programs
testing a last program of every proc
single: executing 1 programs separately with timeout 30s
testing program (duration=30s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program crashed: possible deadlock in n_tty_flush_buffer
single: successfully extracted reproducer
found reproducer with 9 syscalls
minimizing guilty program
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
ioctl$UI_SET_EVBIT(0xffffffffffffffff, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(0xffffffffffffffff, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(0xffffffffffffffff, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(0xffffffffffffffff, 0x5501)
write$input_event(0xffffffffffffffff, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
ioctl$VT_ACTIVATE(0xffffffffffffffff, 0x5606, 0x14)
ioctl$KDSKBENT(0xffffffffffffffff, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r0 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r0, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r0, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r0, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r0, 0x5501)
write$input_event(r0, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, 0x0)
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, 0x0, 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, 0x0)
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program did not crash
testing program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, 0x0, 0x0)

program did not crash
extracting C reproducer
testing compiled C program (duration=39.077381934s, {Threaded:true Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program crashed: possible deadlock in n_tty_flush_buffer
simplifying C reproducer
testing compiled C program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program crashed: possible deadlock in n_tty_flush_buffer
testing compiled C program (duration=39.077381934s, {Threaded:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:false Cgroups:false BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program did not crash
testing compiled C program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox:none SandboxArg:0 Leak:false NetInjection:true NetDevices:true NetReset:true Cgroups:true BinfmtMisc:true CloseFDs:true KCSAN:false DevlinkPCI:false NicVF:false USB:true VhciInjection:true Wifi:true IEEE802154:true Sysctl:true Swap:true UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program did not crash
testing compiled C program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:true Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program crashed: possible deadlock in n_tty_flush_buffer
testing compiled C program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:true HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program crashed: possible deadlock in n_tty_flush_buffer
testing compiled C program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:false HandleSegv:true Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program crashed: possible deadlock in n_tty_flush_buffer
testing compiled C program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:true Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program crashed: possible deadlock in n_tty_flush_buffer
testing compiled C program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
program crashed: possible deadlock in n_tty_flush_buffer
testing program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program crashed: possible deadlock in n_tty_flush_buffer
validation run: crashed=true
testing program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program crashed: possible deadlock in n_tty_flush_buffer
validation run: crashed=true
testing program (duration=39.077381934s, {Threaded:false Repeat:true RepeatTimes:0 Procs:4 Slowdown:1 Sandbox: SandboxArg:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false NicVF:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false Swap:false UseTmpDir:false HandleSegv:false Trace:false CallComments:true LegacyOptions:{Collide:false Fault:false FaultCall:0 FaultNth:0}}): syz_open_dev$tty20-ioctl$VT_ACTIVATE-ioctl$KDSKBENT-openat$uinput-ioctl$UI_SET_EVBIT-ioctl$UI_SET_KEYBIT-ioctl$UI_DEV_SETUP-ioctl$UI_DEV_CREATE-write$input_event
detailed listing:
executing program 0:
r0 = syz_open_dev$tty20(0xc, 0x4, 0x0)
ioctl$VT_ACTIVATE(r0, 0x5606, 0x14)
ioctl$KDSKBENT(r0, 0x4b47, &(0x7f0000000000)={0x0, 0x1c, 0x20f})
r1 = openat$uinput(0xffffffffffffff9c, &(0x7f0000000040), 0x2, 0x0)
ioctl$UI_SET_EVBIT(r1, 0x40045564, 0x1)
ioctl$UI_SET_KEYBIT(r1, 0x40045565, 0x1c)
ioctl$UI_DEV_SETUP(r1, 0x405c5503, &(0x7f0000000080)={{}, 'syz0\x00', 0x1})
ioctl$UI_DEV_CREATE(r1, 0x5501)
write$input_event(r1, &(0x7f0000000100)={{}, 0x1, 0x1c, 0x1}, 0x18)

program crashed: possible deadlock in n_tty_flush_buffer
validation run: crashed=true
reproducing took 17m43.379762394s
repro crashed as (corrupted=false):
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:2/973 is trying to acquire lock:
ffff8880525712c8 (&tty->termios_rwsem){++++}-{4:4}, at: class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
ffff8880525712c8 (&tty->termios_rwsem){++++}-{4:4}, at: n_tty_flush_buffer+0x21/0x1a0 drivers/tty/n_tty.c:349

but task is already holding lock:
ffff888022ee40b8 (&buf->lock){+.+.}-{4:4}, at: tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:236

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&buf->lock){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bc0 kernel/locking/mutex.c:821
       tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:236
       tty_ldisc_flush+0x68/0xf0 drivers/tty/tty_ldisc.c:388
       __do_SAK+0x35f/0x470 drivers/tty/tty_io.c:2998
       vc_SAK+0x7f/0x320 drivers/tty/vt/vt_ioctl.c:998
       process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
       process_scheduled_works kernel/workqueue.c:3470 [inline]
       worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
       kthread+0x373/0x450 kernel/kthread.c:436
       ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (console_lock){+.+.}-{0:0}:
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       console_lock+0x7a/0xa0 kernel/printk/printk.c:2896
       uart_configure_port drivers/tty/serial/serial_core.c:2564 [inline]
       serial_core_add_one_port drivers/tty/serial/serial_core.c:3148 [inline]
       serial_core_register_port+0xf4a/0x1660 drivers/tty/serial/serial_core.c:3353
       serial8250_register_8250_port+0x16c7/0x2440 drivers/tty/serial/8250/8250_core.c:877
       serial_pnp_probe+0x443/0x950 drivers/tty/serial/8250/8250_pnp.c:480
       pnp_device_probe+0x2b3/0x4a0 drivers/pnp/driver.c:111
       call_driver_probe drivers/base/dd.c:628 [inline]
       really_probe+0x241/0xa60 drivers/base/dd.c:706
       __driver_probe_device+0x210/0x460 drivers/base/dd.c:868
       driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
       __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
       bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
       bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
       driver_register+0x1e2/0x360 drivers/base/driver.c:174
       serial8250_init+0xcc/0x1c0 drivers/tty/serial/8250/8250_platform.c:318
       do_one_initcall+0x11c/0x6f0 init/main.c:1357
       do_initcall_level init/main.c:1419 [inline]
       do_initcalls init/main.c:1435 [inline]
       do_basic_setup init/main.c:1455 [inline]
       kernel_init_freeable+0x6ea/0x7b0 init/main.c:1670
       kernel_init+0x21/0x1e0 init/main.c:1560
       ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #1 (&port->mutex){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bc0 kernel/locking/mutex.c:821
       class_mutex_constructor include/linux/mutex.h:253 [inline]
       uart_set_termios+0x8e/0x690 drivers/tty/serial/serial_core.c:1646
       tty_set_termios+0x64d/0x980 drivers/tty/tty_ioctl.c:341
       set_termios+0x5c8/0x880 drivers/tty/tty_ioctl.c:516
       tty_mode_ioctl+0x17e/0xd40 drivers/tty/tty_ioctl.c:803
       n_tty_ioctl_helper+0x47/0x2b0 drivers/tty/tty_ioctl.c:982
       n_tty_ioctl+0x53/0x340 drivers/tty/n_tty.c:2496
       tty_ioctl+0x11b4/0x1640 drivers/tty/tty_io.c:2774
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl fs/ioctl.c:583 [inline]
       __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&tty->termios_rwsem){++++}-{4:4}:
       check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181
       check_prevs_add kernel/locking/lockdep.c:3300 [inline]
       validate_chain kernel/locking/lockdep.c:3924 [inline]
       __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
       class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
       n_tty_flush_buffer+0x21/0x1a0 drivers/tty/n_tty.c:349
       tty_buffer_flush+0x239/0x310 drivers/tty/tty_buffer.c:248
       tty_ldisc_flush+0x68/0xf0 drivers/tty/tty_ldisc.c:388
       __do_SAK+0x35f/0x470 drivers/tty/tty_io.c:2998
       vc_SAK+0x7f/0x320 drivers/tty/vt/vt_ioctl.c:998
       process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
       process_scheduled_works kernel/workqueue.c:3470 [inline]
       worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
       kthread+0x373/0x450 kernel/kthread.c:436
       ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

Chain exists of:
  &tty->termios_rwsem --> console_lock --> &buf->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&buf->lock);
                               lock(console_lock);
                               lock(&buf->lock);
  lock(&tty->termios_rwsem);

 *** DEADLOCK ***

locks held by kworker/0:2/973: 5, last CPU#0:
 #0: ffff88801c0aa940 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3362
 #1: ffffc900051a7d08 ((work_completion)(&vc_cons[currcons].SAK_work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3363
 #2: ffffffff8edd82c0 (console_lock){+.+.}-{0:0}, at: class_console_lock_constructor include/linux/console.h:734 [inline]
 #2: ffffffff8edd82c0 (console_lock){+.+.}-{0:0}, at: vc_SAK+0x13/0x320 drivers/tty/vt/vt_ioctl.c:989
 #3: ffff8880525710a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref drivers/tty/tty_ldisc.c:263 [inline]
 #3: ffff8880525710a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_flush+0x1c/0xf0 drivers/tty/tty_ldisc.c:386
 #4: ffff888022ee40b8 (&buf->lock){+.+.}-{4:4}, at: tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:236

stack backtrace:
CPU: 0 UID: 0 PID: 973 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events vc_SAK
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2059
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2191
 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181
 check_prevs_add kernel/locking/lockdep.c:3300 [inline]
 validate_chain kernel/locking/lockdep.c:3924 [inline]
 __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254
 lock_acquire kernel/locking/lockdep.c:5908 [inline]
 lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
 class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
 n_tty_flush_buffer+0x21/0x1a0 drivers/tty/n_tty.c:349
 tty_buffer_flush+0x239/0x310 drivers/tty/tty_buffer.c:248
 tty_ldisc_flush+0x68/0xf0 drivers/tty/tty_ldisc.c:388
 __do_SAK+0x35f/0x470 drivers/tty/tty_io.c:2998
 vc_SAK+0x7f/0x320 drivers/tty/vt/vt_ioctl.c:998
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
 process_scheduled_works kernel/workqueue.c:3470 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
tty tty20: SAK: killed process 6512 (syz.0.501): by fd#3
tty tty20: SAK: killed process 6522 (syz.0.512): by fd#3
tty tty20: SAK: killed process 6545 (syz.0.535): by fd#3
tty tty20: SAK: killed process 6565 (syz.0.555): by fd#3
tty tty20: SAK: killed process 6870 (syz.0.860): by fd#3
tty tty20: SAK: killed process 6936 (syz.0.925): by fd#3
tty tty20: SAK: killed process 6948 (syz.0.938): by fd#3
tty tty20: SAK: killed process 6965 (syz.0.955): by fd#3
tty tty20: SAK: killed process 6969 (syz.0.959): by fd#3
tty tty20: SAK: killed process 7002 (syz.0.989): by fd#3
tty tty20: SAK: killed process 7015 (syz.0.1002): by fd#3

final repro crashed as (corrupted=false):
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:2/973 is trying to acquire lock:
ffff8880525712c8 (&tty->termios_rwsem){++++}-{4:4}, at: class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
ffff8880525712c8 (&tty->termios_rwsem){++++}-{4:4}, at: n_tty_flush_buffer+0x21/0x1a0 drivers/tty/n_tty.c:349

but task is already holding lock:
ffff888022ee40b8 (&buf->lock){+.+.}-{4:4}, at: tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:236

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&buf->lock){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bc0 kernel/locking/mutex.c:821
       tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:236
       tty_ldisc_flush+0x68/0xf0 drivers/tty/tty_ldisc.c:388
       __do_SAK+0x35f/0x470 drivers/tty/tty_io.c:2998
       vc_SAK+0x7f/0x320 drivers/tty/vt/vt_ioctl.c:998
       process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
       process_scheduled_works kernel/workqueue.c:3470 [inline]
       worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
       kthread+0x373/0x450 kernel/kthread.c:436
       ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (console_lock){+.+.}-{0:0}:
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       console_lock+0x7a/0xa0 kernel/printk/printk.c:2896
       uart_configure_port drivers/tty/serial/serial_core.c:2564 [inline]
       serial_core_add_one_port drivers/tty/serial/serial_core.c:3148 [inline]
       serial_core_register_port+0xf4a/0x1660 drivers/tty/serial/serial_core.c:3353
       serial8250_register_8250_port+0x16c7/0x2440 drivers/tty/serial/8250/8250_core.c:877
       serial_pnp_probe+0x443/0x950 drivers/tty/serial/8250/8250_pnp.c:480
       pnp_device_probe+0x2b3/0x4a0 drivers/pnp/driver.c:111
       call_driver_probe drivers/base/dd.c:628 [inline]
       really_probe+0x241/0xa60 drivers/base/dd.c:706
       __driver_probe_device+0x210/0x460 drivers/base/dd.c:868
       driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
       __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
       bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
       bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
       driver_register+0x1e2/0x360 drivers/base/driver.c:174
       serial8250_init+0xcc/0x1c0 drivers/tty/serial/8250/8250_platform.c:318
       do_one_initcall+0x11c/0x6f0 init/main.c:1357
       do_initcall_level init/main.c:1419 [inline]
       do_initcalls init/main.c:1435 [inline]
       do_basic_setup init/main.c:1455 [inline]
       kernel_init_freeable+0x6ea/0x7b0 init/main.c:1670
       kernel_init+0x21/0x1e0 init/main.c:1560
       ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #1 (&port->mutex){+.+.}-{4:4}:
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       __mutex_lock_common kernel/locking/mutex.c:646 [inline]
       __mutex_lock+0x1a4/0x1bc0 kernel/locking/mutex.c:821
       class_mutex_constructor include/linux/mutex.h:253 [inline]
       uart_set_termios+0x8e/0x690 drivers/tty/serial/serial_core.c:1646
       tty_set_termios+0x64d/0x980 drivers/tty/tty_ioctl.c:341
       set_termios+0x5c8/0x880 drivers/tty/tty_ioctl.c:516
       tty_mode_ioctl+0x17e/0xd40 drivers/tty/tty_ioctl.c:803
       n_tty_ioctl_helper+0x47/0x2b0 drivers/tty/tty_ioctl.c:982
       n_tty_ioctl+0x53/0x340 drivers/tty/n_tty.c:2496
       tty_ioctl+0x11b4/0x1640 drivers/tty/tty_io.c:2774
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:597 [inline]
       __se_sys_ioctl fs/ioctl.c:583 [inline]
       __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
       do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
       do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&tty->termios_rwsem){++++}-{4:4}:
       check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181
       check_prevs_add kernel/locking/lockdep.c:3300 [inline]
       validate_chain kernel/locking/lockdep.c:3924 [inline]
       __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254
       lock_acquire kernel/locking/lockdep.c:5908 [inline]
       lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
       down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
       class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
       n_tty_flush_buffer+0x21/0x1a0 drivers/tty/n_tty.c:349
       tty_buffer_flush+0x239/0x310 drivers/tty/tty_buffer.c:248
       tty_ldisc_flush+0x68/0xf0 drivers/tty/tty_ldisc.c:388
       __do_SAK+0x35f/0x470 drivers/tty/tty_io.c:2998
       vc_SAK+0x7f/0x320 drivers/tty/vt/vt_ioctl.c:998
       process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
       process_scheduled_works kernel/workqueue.c:3470 [inline]
       worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
       kthread+0x373/0x450 kernel/kthread.c:436
       ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

Chain exists of:
  &tty->termios_rwsem --> console_lock --> &buf->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&buf->lock);
                               lock(console_lock);
                               lock(&buf->lock);
  lock(&tty->termios_rwsem);

 *** DEADLOCK ***

locks held by kworker/0:2/973: 5, last CPU#0:
 #0: ffff88801c0aa940 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1466/0x1b10 kernel/workqueue.c:3362
 #1: ffffc900051a7d08 ((work_completion)(&vc_cons[currcons].SAK_work)){+.+.}-{0:0}, at: process_one_work+0xa2c/0x1b10 kernel/workqueue.c:3363
 #2: ffffffff8edd82c0 (console_lock){+.+.}-{0:0}, at: class_console_lock_constructor include/linux/console.h:734 [inline]
 #2: ffffffff8edd82c0 (console_lock){+.+.}-{0:0}, at: vc_SAK+0x13/0x320 drivers/tty/vt/vt_ioctl.c:989
 #3: ffff8880525710a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref drivers/tty/tty_ldisc.c:263 [inline]
 #3: ffff8880525710a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_flush+0x1c/0xf0 drivers/tty/tty_ldisc.c:386
 #4: ffff888022ee40b8 (&buf->lock){+.+.}-{4:4}, at: tty_buffer_flush+0x72/0x310 drivers/tty/tty_buffer.c:236

stack backtrace:
CPU: 0 UID: 0 PID: 973 Comm: kworker/0:2 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events vc_SAK
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_circular_bug.cold+0x178/0x1be kernel/locking/lockdep.c:2059
 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2191
 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3181
 check_prevs_add kernel/locking/lockdep.c:3300 [inline]
 validate_chain kernel/locking/lockdep.c:3924 [inline]
 __lock_acquire+0x1492/0x1ec0 kernel/locking/lockdep.c:5254
 lock_acquire kernel/locking/lockdep.c:5908 [inline]
 lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5865
 down_write+0x8b/0x1f0 kernel/locking/rwsem.c:1631
 class_rwsem_write_constructor include/linux/rwsem.h:270 [inline]
 n_tty_flush_buffer+0x21/0x1a0 drivers/tty/n_tty.c:349
 tty_buffer_flush+0x239/0x310 drivers/tty/tty_buffer.c:248
 tty_ldisc_flush+0x68/0xf0 drivers/tty/tty_ldisc.c:388
 __do_SAK+0x35f/0x470 drivers/tty/tty_io.c:2998
 vc_SAK+0x7f/0x320 drivers/tty/vt/vt_ioctl.c:998
 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387
 process_scheduled_works kernel/workqueue.c:3470 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551
 kthread+0x373/0x450 kernel/kthread.c:436
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
tty tty20: SAK: killed process 6512 (syz.0.501): by fd#3
tty tty20: SAK: killed process 6522 (syz.0.512): by fd#3
tty tty20: SAK: killed process 6545 (syz.0.535): by fd#3
tty tty20: SAK: killed process 6565 (syz.0.555): by fd#3
tty tty20: SAK: killed process 6870 (syz.0.860): by fd#3
tty tty20: SAK: killed process 6936 (syz.0.925): by fd#3
tty tty20: SAK: killed process 6948 (syz.0.938): by fd#3
tty tty20: SAK: killed process 6965 (syz.0.955): by fd#3
tty tty20: SAK: killed process 6969 (syz.0.959): by fd#3
tty tty20: SAK: killed process 7002 (syz.0.989): by fd#3
tty tty20: SAK: killed process 7015 (syz.0.1002): by fd#3