Re: BUG: unable to handle kernel paging request in __get_user_4

[Dmitry Vyukov]

On Sun, Dec 3, 2017 at 3:23 PM, syzbot
<bot+526b7120b487f61c779d3cadfc1befe4cfe62b54@xxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hello,
>
> syzkaller hit the following crash on
> fb20eb9d798d2f4c1a75b7fe981d72dfa8d7270d
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
>
> Unfortunately, I don't have any reproducer for this bug yet.
>
>
> Bearer <> rejected, not supported in standalone mode
> kvm: pic: non byte read
> BUG: unable to handle kernel paging request at 000000009bac8456
> IP: __get_user_4+0x1e/0x30 arch/x86/lib/getuser.S:72
> PGD 5e28067 P4D 5e28067 PUD 5e2a067 PMD 0
> Oops: 0002 [#1] SMP KASAN
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Modules linked in:
> CPU: 0 PID: 5282 Comm: syz-executor4 Not tainted 4.15.0-rc1-next-20171201+
> #57
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> task: 00000000aec8ff4d task.stack: 00000000b2f5be93
> RIP: 0010:__get_user_4+0x1e/0x30 arch/x86/lib/getuser.S:72
> RSP: 0018:ffff8801c69f7c98 EFLAGS: 00010283
> RAX: 0000000020000007 RBX: fffffffffffffff2 RCX: ffffffff8199e758
> RDX: 0000000000000078 RSI: ffffc9000376d000 RDI: 0000000000000282
> RBP: ffff8801c69f7f10 R08: ffff8801db41f740 R09: 1ffff10038d3ef68
> R10: ffff8801919ec4c0 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000020000000 R14: ffff8801c69f7e48 R15: 0000000000000000
> FS:  00007f8945789700(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: fffffffffffffff8 CR3: 00000001cc3af000 CR4: 00000000001426f0
> DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff1 DR7: 00000000000b0602
> Call Trace:
>  SyS_perf_event_open+0x39/0x50 kernel/events/core.c:9825
>  entry_SYSCALL_64_fastpath+0x1f/0x96
> RIP: 0033:0x4529d9
> RSP: 002b:00007f8945788c58 EFLAGS: 00000212 ORIG_RAX: 000000000000012a
> RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 00000000004529d9
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000000
> RBP: 00000000000005a8 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffffffffffffff R11: 0000000000000212 R12: 00000000006f5860
> R13: 00000000ffffffff R14: 00007f89457896d4 R15: 0000000000000000
> Code: 00 c3 90 66 2e 0f 1f 84 00 00 00 00 00 48 83 c0 03 72 4f 65 48 8b 14
> 25 40 65 01 00 48 3b 82 a0 15 00 00 73 3d 0f 1f 00 8b 50 fd <31> c0 0f 1f 00
> c3 66 90 66 2e 0f 1f 84 00 00 00 00 00 48 83 c0
> RIP: __get_user_4+0x1e/0x30 arch/x86/lib/getuser.S:72 RSP: ffff8801c69f7c98
> CR2: fffffffffffffff8
> ---[ end trace 8461d08d2284fad0 ]---
> Kernel panic - not syncing: Fatal exception
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Kernel Offset: disabled
> Rebooting in 86400 seconds..

#syz dup: BUG: unable to handle kernel paging request in __switch_to

> ---
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> See https://goo.gl/tpsmEJ for details.
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