Re: BUG: unable to handle kernel NULL pointer dereference in corrupted (2)

[Dmitry Vyukov]

On Wed, Jul 18, 2018 at 6:29 AM, syzbot
<syzbot+c9ebf7fd9683e40ccebc@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    dc989d2ce2c2 tools: bpftool: don't pass FEATURES_DUMP to l..
> git tree:       bpf-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=10a9a978400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=89129667b46496c3
> dashboard link: https://syzkaller.appspot.com/bug?extid=c9ebf7fd9683e40ccebc
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=11974b2c400000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14de7a58400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+c9ebf7fd9683e40ccebc@xxxxxxxxxxxxxxxxxxxxxxxxx

#syz fix: bpf: sockhash, disallow bpf_tcp_close and update in parallel

> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> random: sshd: uninitialized urandom read (32 bytes read)
> IPVS: ftp: loaded support on port[0] = 21
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000072
> ==================================================================
> PGD 1acfe1067
> BUG: KASAN: stack-out-of-bounds in rcu_cblist_dequeue+0xaa/0xe0
> kernel/rcu/rcu_segcblist.c:54
> P4D 1acfe1067
> Read of size 8 at addr ffff8801cfe1e340 by task syz-executor568/12240
> PUD 1c551a067
>
> PMD 0
> CPU: 0 PID: 12240 Comm: syz-executor568 Not tainted 4.18.0-rc3+ #57
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Oops: 0002 [#1] SMP KASAN
> Call Trace:
> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.18.0-rc3+ #57
>  <IRQ>
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
> RIP: 0010:K512_4+0x6792/0x120eac
> Code:
> 20
> 36
> 34
>  print_address_description+0x6c/0x20b mm/kasan/report.c:256
> 20
> 34
>  kasan_report_error mm/kasan/report.c:354 [inline]
>  kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
> 20
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
> 74
>  rcu_cblist_dequeue+0xaa/0xe0 kernel/rcu/rcu_segcblist.c:54
> 68
> 69
>  rcu_do_batch kernel/rcu/tree.c:2556 [inline]
>  invoke_rcu_callbacks kernel/rcu/tree.c:2818 [inline]
>  __rcu_process_callbacks kernel/rcu/tree.c:2785 [inline]
>  rcu_process_callbacks+0xf7e/0x1850 kernel/rcu/tree.c:2802
> 73
> 20
> 32
> 35
> 36
> 20
> 36
> 34
> 20
> 34
> 20
>  __do_softirq+0x2e8/0xb17 kernel/softirq.c:288
> 74
> 68
> 61
> 74
> 20
> 00
> 00
> 00
> 00
> 00
>  invoke_softirq kernel/softirq.c:368 [inline]
>  irq_exit+0x1d1/0x200 kernel/softirq.c:408
> 00
>  exiting_irq arch/x86/include/asm/apic.h:527 [inline]
>  smp_apic_timer_interrupt+0x186/0x730 arch/x86/kernel/apic/apic.c:1052
> 00
> 20
> 30
> 20
> 33
> 32
> 20
> 38
>  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
> 20
>  </IRQ>
> 31
>
> 32
> Allocated by task 0:
> <20>
> (stack is not available)
> 74
>
> 61
> Freed by task 3487688240:
> 72 67 65 74 5f 65 6e 74 72 79 20 39 36 20 32 34 20 35 20
> RSP: 0018:ffff8801daf07980 EFLAGS: 00010202
> RAX: ffffffff81674dc6 RBX: ffffffff88bf2c08 RCX: 0000000000000000
> RDX: ffffffff88bf2c08 RSI: 0000000000000000 RDI: ffff8801cfea94a0
> RBP: ffff8801daf07c88 R08: 0000000000000000 R09: 0000000000000000
> R10: fffffbfff157bc71 R11: ffffffff8abde38b R12: ffff8801cfea94a0
> R13: ffff8801cfea94a8 R14: dffffc0000000000 R15: ffff8801daf07c60
> FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000072 CR3: 00000001cae8d000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <IRQ>
>  __do_softirq+0x2e8/0xb17 kernel/softirq.c:288
>  invoke_softirq kernel/softirq.c:368 [inline]
>  irq_exit+0x1d1/0x200 kernel/softirq.c:408
>  exiting_irq arch/x86/include/asm/apic.h:527 [inline]
>  smp_apic_timer_interrupt+0x186/0x730 arch/x86/kernel/apic/apic.c:1052
>  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
>  </IRQ>
> RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54
> Code: c7 48 89 45 d8 e8 8a 2d 23 fa 48 8b 45 d8 e9 d2 fe ff ff 48 89 df e8
> 79 2d 23 fa eb 8a 90 90 90 90 90 90 90 55 48 89 e5 fb f4 <5d> c3 0f 1f 84 00
> 00 00 00 00 55 48 89 e5 f4 5d c3 90 90 90 90 90
> RSP: 0018:ffff8801d9af7c38 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
> RAX: dffffc0000000000 RBX: 1ffff1003b35ef8a RCX: ffffffff81667982
> RDX: 1ffffffff11e3610 RSI: 0000000000000004 RDI: ffffffff88f1b080
> RBP: ffff8801d9af7c38 R08: ffffed003b5e46d7 R09: ffffed003b5e46d6
> R10: ffffed003b5e46d6 R11: ffff8801daf236b3 R12: 0000000000000001
> R13: ffff8801d9af7cf0 R14: ffffffff899ee920 R15: 0000000000000000
>  arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
>  default_idle+0xc7/0x450 arch/x86/kernel/process.c:500
>  arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:491
>  default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
>  cpuidle_idle_call kernel/sched/idle.c:153 [inline]
>  do_idle+0x3aa/0x570 kernel/sched/idle.c:262
>  cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
>  start_secondary+0x433/0x5d0 arch/x86/kernel/smpboot.c:265
>  secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242
> Modules linked in:
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> CR2: 0000000000000072
> ---[ end trace 9d01a82a0b66f200 ]---
> BUG: unable to handle kernel paging request at ffffffff8c3f7968
> PGD 8e6d067
> RIP: 0010:K512_4+0x6792/0x120eac
> P4D 8e6d067
> Code:
> PUD 8e6e063
> 20
> PMD 0
> 36
> 34
> Thread overran stack, or stack corrupted
> 20 34
> Oops: 0000 [#2] SMP KASAN
> 20
> CPU: 0 PID: 12240 Comm: syz-executor568 Tainted: G      D
> 4.18.0-rc3+ #57
> 74
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> 68
> RIP: 0010:depot_fetch_stack+0x10/0x30 lib/stackdepot.c:201
> 69
> Code:
> 73
> e8
> 20
> c5
> 32
> 2e
> 35
> 47
> 36
> fe
> 20
> e9
> 36
> b3
> 34
> fd
> 20
> ff
> 34
> ff
> 20
> e8
> 74
> bb
> 68
> 2e
> 61
> 47
> 74
> fe
> 20
> e9
> 00
> 55
> 00
> fd
> 00
> ff
> 00
> ff
> 00
> 90
> 00
> 90
> 00
> 90
> 20
> 90
> 30
> 90
> 20
> 90
> 33
> 89
> 32
> f8
> 20
> c1
> 38
> ef
> 20
> 11
> 31
> 25
> 32
> ff
> <20>
> ff
> 74
> 1f
> 61
> 00
> 72
> 81
> 67
> e7
> 65
> f0
> 74
> 3f
> 5f
> 00
> 65
> 00
> 6e
> <48>
> 74
> 03
> 72
> 3c
> 79
> c5
> 20
> 60
> 39
> 39
> 36
> 43
> 20
> 8b
> 32
> 8b
> 34
> 47
> 20
> 0c
> 35
> 48
> 20
> 83
> c7
> RSP: 0018:ffff8801daf07980 EFLAGS: 00010202
> 18
> c7
> RAX: ffffffff81674dc6 RBX: ffffffff88bf2c08 RCX: 0000000000000000
> 46 10
> RDX: ffffffff88bf2c08 RSI: 0000000000000000 RDI: ffff8801cfea94a0
> 00
> RBP: ffff8801daf07c88 R08: 0000000000000000 R09: 0000000000000000
> 00
> R10: fffffbfff157bc71 R11: ffffffff8abde38b R12: ffff8801cfea94a0
> 00
> R13: ffff8801cfea94a8 R14: dffffc0000000000 R15: ffff8801daf07c60
> 00
> FS:  0000000000000000(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> RSP: 0018:ffff8801dae07898 EFLAGS: 00010006
> CR2: 0000000000000072 CR3: 00000001cae8d000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> RAX: 00000000001f8801 RBX: ffff8801cfe1e514 RCX: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> RDX: 0000000000000000 RSI: ffff8801dae078a0 RDI: 0000000000003ff0
>
>
> ---
> This bug 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@xxxxxxxxxxxxxxxxx
>
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> syzbot can test patches for this bug, for details see:
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>
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