syzbot

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html for details.
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 5335 Comm: syz-executor364 Not tainted 4.19.0-rc4+ #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__fire_sched_out_preempt_notifiers kernel/sched/core.c:2497 [inline]
RIP: 0010:fire_sched_out_preempt_notifiers kernel/sched/core.c:2505 [inline]
RIP: 0010:prepare_task_switch kernel/sched/core.c:2611 [inline]
RIP: 0010:context_switch kernel/sched/core.c:2790 [inline]
RIP: 0010:__schedule+0xfb7/0x1ed0 kernel/sched/core.c:3473
Code: 89 e0 48 c1 e8 03 42 80 3c 28 00 0f 85 b9 09 00 00 4d 8b 24 24 4d 85 e4 0f 84 0b f7 ff ff 49 8d 7c 24 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 a4 e8 ed ed 03 fa eb 9d 48 89 de 4c 89 ff e8 00
RSP: 0018:ffff8801cbf96bd0 EFLAGS: 00010806
RAX: 1bd5a00000000022 RBX: ffff8801bc9780c0 RCX: 1ffff1003978f88f
RDX: 0000000040000000 RSI: 0000000000000000 RDI: dead000000000110
RBP: ffff8801cbf96da8 R08: ffff8801d7c08600 R09: fffff520003c8e47
R10: fffff520003c8e47 R11: ffffc90001e4723b R12: dead000000000100
R13: dffffc0000000000 R14: ffff8801daf2cb40 R15: ffff8801d7c08600
FS:  00000000020d7880(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000043eede CR3: 000000000946a000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 preempt_schedule_common+0x1f/0xd0 kernel/sched/core.c:3597
 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3623
 ___preempt_schedule+0x16/0x18
 on_each_cpu+0x1ab/0x1e0 kernel/smp.c:608
 text_poke_bp+0x14e/0x1de arch/x86/kernel/alternative.c:822
 __jump_label_transform.isra.0+0x478/0x8f0 arch/x86/kernel/jump_label.c:105
 arch_jump_label_transform+0x2f/0x40 arch/x86/kernel/jump_label.c:113
 __jump_label_update+0x16e/0x1a0 kernel/jump_label.c:375
 jump_label_update+0x174/0x320 kernel/jump_label.c:760
 __static_key_slow_dec_cpuslocked+0xb8/0x210 kernel/jump_label.c:205
 __static_key_slow_dec kernel/jump_label.c:215 [inline]
 static_key_slow_dec+0x63/0xa0 kernel/jump_label.c:229
 kvm_arch_vcpu_uninit+0x18e/0x1d0 arch/x86/kvm/x86.c:8822
 kvm_vcpu_uninit+0x44/0x90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:337
 vmx_free_vcpu+0x23a/0x300 arch/x86/kvm/vmx.c:10947
 kvm_arch_vcpu_free arch/x86/kvm/x86.c:8438 [inline]
 kvm_free_vcpus arch/x86/kvm/x86.c:8888 [inline]
 kvm_arch_destroy_vm+0x365/0x7c0 arch/x86/kvm/x86.c:8985
 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:752 [inline]
 kvm_put_kvm+0x6c8/0xff0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:773
 kvm_vm_release+0x42/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:784
 __fput+0x385/0xa30 fs/file_table.c:278
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1ad7/0x2610 kernel/exit.c:867
 do_group_exit+0x177/0x440 kernel/exit.c:970
 __do_sys_exit_group kernel/exit.c:981 [inline]
 __se_sys_exit_group kernel/exit.c:979 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:979
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43ef08
Code: Bad RIP value.
RSP: 002b:00007ffd60a5eb28 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ef08
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004be7c8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 00000000004002c8 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:

======================================================
WARNING: possible circular locking dependency detected
4.19.0-rc4+ #25 Not tainted
------------------------------------------------------
syz-executor364/5335 is trying to acquire lock:
00000000a15f472e ((console_sem).lock){-...}, at: down_trylock+0x13/0x70 kernel/locking/semaphore.c:136

but task is already holding lock:
00000000cccdf9ce (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1821 [inline]
00000000cccdf9ce (&rq->lock){-.-.}, at: __schedule+0x236/0x1ed0 kernel/sched/core.c:3411

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&rq->lock){-.-.}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
       _raw_spin_lock+0x2d/0x40 kernel/locking/spinlock.c:144
       rq_lock kernel/sched/sched.h:1821 [inline]
       task_fork_fair+0xb0/0x6d0 kernel/sched/fair.c:9581
       sched_fork+0x443/0xba0 kernel/sched/core.c:2353
       copy_process+0x2586/0x8780 kernel/fork.c:1839
       _do_fork+0x1cb/0x11d0 kernel/fork.c:2166
       kernel_thread+0x34/0x40 kernel/fork.c:2225
       rest_init+0x22/0xe5 init/main.c:408
       start_kernel+0x8f4/0x92f init/main.c:739
       x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
       x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
       secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

-> #1 (&p->pi_lock){-.-.}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
       try_to_wake_up+0xd2/0x12f0 kernel/sched/core.c:1960
       wake_up_process+0x10/0x20 kernel/sched/core.c:2123
       __up.isra.1+0x1c0/0x2a0 kernel/locking/semaphore.c:262
       up+0x13c/0x1c0 kernel/locking/semaphore.c:187
       __up_console_sem+0xbe/0x1b0 kernel/printk/printk.c:244
       console_unlock+0x814/0x1160 kernel/printk/printk.c:2427
       vprintk_emit+0x33d/0x930 kernel/printk/printk.c:1922
       vprintk_default+0x28/0x30 kernel/printk/printk.c:1963
       vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
       printk+0xa7/0xcf kernel/printk/printk.c:1996
       load_umh+0x51/0xbd net/bpfilter/bpfilter_kern.c:98
       do_one_initcall+0x145/0x957 init/main.c:885
       do_initcall_level init/main.c:953 [inline]
       do_initcalls init/main.c:961 [inline]
       do_basic_setup init/main.c:979 [inline]
       kernel_init_freeable+0x4bb/0x5ae init/main.c:1144
       kernel_init+0x11/0x1b2 init/main.c:1063
       ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413

-> #0 ((console_sem).lock){-...}:
       lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
       down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
       __down_trylock_console_sem+0xae/0x200 kernel/printk/printk.c:227
       console_trylock+0x15/0xa0 kernel/printk/printk.c:2245
       console_trylock_spinning kernel/printk/printk.c:1649 [inline]
       vprintk_emit+0x322/0x930 kernel/printk/printk.c:1921
       vprintk_default+0x28/0x30 kernel/printk/printk.c:1963
       vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
       printk+0xa7/0xcf kernel/printk/printk.c:1996
       kasan_die_handler.cold.22+0x11/0x30 arch/x86/mm/kasan_init_64.c:251
       notifier_call_chain+0x17e/0x380 kernel/notifier.c:93
       __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
       atomic_notifier_call_chain+0x96/0x190 kernel/notifier.c:193
       notify_die+0x1bd/0x2d0 kernel/notifier.c:549
       do_general_protection+0x248/0x2f0 arch/x86/kernel/traps.c:559
       general_protection+0x1e/0x30 arch/x86/entry/entry_64.S:1160
       __fire_sched_out_preempt_notifiers kernel/sched/core.c:2497 [inline]
       fire_sched_out_preempt_notifiers kernel/sched/core.c:2505 [inline]
       prepare_task_switch kernel/sched/core.c:2611 [inline]
       context_switch kernel/sched/core.c:2790 [inline]
       __schedule+0xfb7/0x1ed0 kernel/sched/core.c:3473
       preempt_schedule_common+0x1f/0xd0 kernel/sched/core.c:3597
       preempt_schedule+0x4d/0x60 kernel/sched/core.c:3623
       ___preempt_schedule+0x16/0x18
       on_each_cpu+0x1ab/0x1e0 kernel/smp.c:608
       text_poke_bp+0x14e/0x1de arch/x86/kernel/alternative.c:822
       __jump_label_transform.isra.0+0x478/0x8f0 arch/x86/kernel/jump_label.c:105
       arch_jump_label_transform+0x2f/0x40 arch/x86/kernel/jump_label.c:113
       __jump_label_update+0x16e/0x1a0 kernel/jump_label.c:375
       jump_label_update+0x174/0x320 kernel/jump_label.c:760
       __static_key_slow_dec_cpuslocked+0xb8/0x210 kernel/jump_label.c:205
       __static_key_slow_dec kernel/jump_label.c:215 [inline]
       static_key_slow_dec+0x63/0xa0 kernel/jump_label.c:229
       kvm_arch_vcpu_uninit+0x18e/0x1d0 arch/x86/kvm/x86.c:8822
       kvm_vcpu_uninit+0x44/0x90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:337
       vmx_free_vcpu+0x23a/0x300 arch/x86/kvm/vmx.c:10947
       kvm_arch_vcpu_free arch/x86/kvm/x86.c:8438 [inline]
       kvm_free_vcpus arch/x86/kvm/x86.c:8888 [inline]
       kvm_arch_destroy_vm+0x365/0x7c0 arch/x86/kvm/x86.c:8985
       kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:752 [inline]
       kvm_put_kvm+0x6c8/0xff0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:773
       kvm_vm_release+0x42/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:784
       __fput+0x385/0xa30 fs/file_table.c:278
       ____fput+0x15/0x20 fs/file_table.c:309
       task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
       exit_task_work include/linux/task_work.h:22 [inline]
       do_exit+0x1ad7/0x2610 kernel/exit.c:867
       do_group_exit+0x177/0x440 kernel/exit.c:970
       __do_sys_exit_group kernel/exit.c:981 [inline]
       __se_sys_exit_group kernel/exit.c:979 [inline]
       __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:979
       do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

Chain exists of:
  (console_sem).lock --> &p->pi_lock --> &rq->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rq->lock);
                               lock(&p->pi_lock);
                               lock(&rq->lock);
  lock((console_sem).lock);

 *** DEADLOCK ***

5 locks held by syz-executor364/5335:
 #0: 00000000916b79a9 (cpu_hotplug_lock.rw_sem){++++}, at: __static_key_slow_dec kernel/jump_label.c:214 [inline]
 #0: 00000000916b79a9 (cpu_hotplug_lock.rw_sem){++++}, at: static_key_slow_dec+0x57/0xa0 kernel/jump_label.c:229
 #1: 00000000ca0bb087 (jump_label_mutex){+.+.}, at: __static_key_slow_dec_cpuslocked+0x82/0x210 kernel/jump_label.c:195
 #2: 00000000f94994a3 (text_mutex){+.+.}, at: arch_jump_label_transform+0x1b/0x40 arch/x86/kernel/jump_label.c:112
 #3: 00000000cccdf9ce (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1821 [inline]
 #3: 00000000cccdf9ce (&rq->lock){-.-.}, at: __schedule+0x236/0x1ed0 kernel/sched/core.c:3411
 #4: 00000000e63739c2 (rcu_read_lock){....}, at: atomic_notifier_call_chain+0x0/0x190 kernel/notifier.c:329

stack backtrace:
CPU: 1 PID: 5335 Comm: syz-executor364 Not tainted 4.19.0-rc4+ #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
 print_circular_bug.isra.33.cold.54+0x1bd/0x27d kernel/locking/lockdep.c:1221
 check_prev_add kernel/locking/lockdep.c:1861 [inline]
 check_prevs_add kernel/locking/lockdep.c:1974 [inline]
 validate_chain kernel/locking/lockdep.c:2415 [inline]
 __lock_acquire+0x33e4/0x4ec0 kernel/locking/lockdep.c:3411
 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152
 down_trylock+0x13/0x70 kernel/locking/semaphore.c:136
 __down_trylock_console_sem+0xae/0x200 kernel/printk/printk.c:227
 console_trylock+0x15/0xa0 kernel/printk/printk.c:2245
 console_trylock_spinning kernel/printk/printk.c:1649 [inline]
 vprintk_emit+0x322/0x930 kernel/printk/printk.c:1921
 vprintk_default+0x28/0x30 kernel/printk/printk.c:1963
 vprintk_func+0x7e/0x181 kernel/printk/printk_safe.c:398
 printk+0xa7/0xcf kernel/printk/printk.c:1996
 kasan_die_handler.cold.22+0x11/0x30 arch/x86/mm/kasan_init_64.c:251
 notifier_call_chain+0x17e/0x380 kernel/notifier.c:93
 __atomic_notifier_call_chain kernel/notifier.c:183 [inline]
 atomic_notifier_call_chain+0x96/0x190 kernel/notifier.c:193
 notify_die+0x1bd/0x2d0 kernel/notifier.c:549
 do_general_protection+0x248/0x2f0 arch/x86/kernel/traps.c:559
 general_protection+0x1e/0x30 arch/x86/entry/entry_64.S:1160
RIP: 0010:__fire_sched_out_preempt_notifiers kernel/sched/core.c:2497 [inline]
RIP: 0010:fire_sched_out_preempt_notifiers kernel/sched/core.c:2505 [inline]
RIP: 0010:prepare_task_switch kernel/sched/core.c:2611 [inline]
RIP: 0010:context_switch kernel/sched/core.c:2790 [inline]
RIP: 0010:__schedule+0xfb7/0x1ed0 kernel/sched/core.c:3473
Code: 89 e0 48 c1 e8 03 42 80 3c 28 00 0f 85 b9 09 00 00 4d 8b 24 24 4d 85 e4 0f 84 0b f7 ff ff 49 8d 7c 24 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 a4 e8 ed ed 03 fa eb 9d 48 89 de 4c 89 ff e8 00
RSP: 0018:ffff8801cbf96bd0 EFLAGS: 00010806
RAX: 1bd5a00000000022 RBX: ffff8801bc9780c0 RCX: 1ffff1003978f88f
RDX: 0000000040000000 RSI: 0000000000000000 RDI: dead000000000110
RBP: ffff8801cbf96da8 R08: ffff8801d7c08600 R09: fffff520003c8e47
R10: fffff520003c8e47 R11: ffffc90001e4723b R12: dead000000000100
R13: dffffc0000000000 R14: ffff8801daf2cb40 R15: ffff8801d7c08600
 preempt_schedule_common+0x1f/0xd0 kernel/sched/core.c:3597
 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3623
 ___preempt_schedule+0x16/0x18
 on_each_cpu+0x1ab/0x1e0 kernel/smp.c:608
 text_poke_bp+0x14e/0x1de arch/x86/kernel/alternative.c:822
 __jump_label_transform.isra.0+0x478/0x8f0 arch/x86/kernel/jump_label.c:105
 arch_jump_label_transform+0x2f/0x40 arch/x86/kernel/jump_label.c:113
 __jump_label_update+0x16e/0x1a0 kernel/jump_label.c:375
 jump_label_update+0x174/0x320 kernel/jump_label.c:760
 __static_key_slow_dec_cpuslocked+0xb8/0x210 kernel/jump_label.c:205
 __static_key_slow_dec kernel/jump_label.c:215 [inline]
 static_key_slow_dec+0x63/0xa0 kernel/jump_label.c:229
 kvm_arch_vcpu_uninit+0x18e/0x1d0 arch/x86/kvm/x86.c:8822
 kvm_vcpu_uninit+0x44/0x90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:337
 vm
Lost 98 message(s)!
---[ end trace 50bd89360bd97ced ]---
RIP: 0010:__fire_sched_out_preempt_notifiers kernel/sched/core.c:2497 [inline]
RIP: 0010:fire_sched_out_preempt_notifiers kernel/sched/core.c:2505 [inline]
RIP: 0010:prepare_task_switch kernel/sched/core.c:2611 [inline]
RIP: 0010:context_switch kernel/sched/core.c:2790 [inline]
RIP: 0010:__schedule+0xfb7/0x1ed0 kernel/sched/core.c:3473
Code: 89 e0 48 c1 e8 03 42 80 3c 28 00 0f 85 b9 09 00 00 4d 8b 24 24 4d 85 e4 0f 84 0b f7 ff ff 49 8d 7c 24 10 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 74 a4 e8 ed ed 03 fa eb 9d 48 89 de 4c 89 ff e8 00
RSP: 0018:ffff8801cbf96bd0 EFLAGS: 00010806
RAX: 1bd5a00000000022 RBX: ffff8801bc9780c0 RCX: 1ffff1003978f88f
RDX: 0000000040000000 RSI: 0000000000000000 RDI: dead000000000110
RBP: ffff8801cbf96da8 R08: ffff8801d7c08600 R09: fffff520003c8e47
R10: fffff520003c8e47 R11: ffffc90001e4723b R12: dead000000000100
R13: dffffc0000000000 R14: ffff8801daf2cb40 R15: ffff8801d7c08600
FS:  00000000020d7880(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000043eede CR3: 000000000946a000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400