Message-ID: <CACT4Y+bXkW-pBuYyGppoizE4EiFxjeOKzLYTy7H3XsJccbXX5w@mail.gmail.com>
Date:   Sat, 18 Apr 2020 08:55:09 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     syzbot <syzbot+a0f91e07da410c63b9c3@...kaller.appspotmail.com>
Cc:     Christian Brauner <christian@...uner.io>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: general protection fault in mm_update_next_owner (2)

On Sat, Apr 18, 2020 at 8:44 AM syzbot
<syzbot+a0f91e07da410c63b9c3@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    8f3d9f35 Linux 5.7-rc1
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=119a1c07e00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=5d351a1019ed81a2
> dashboard link: https://syzkaller.appspot.com/bug?extid=a0f91e07da410c63b9c3
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+a0f91e07da410c63b9c3@...kaller.appspotmail.com

FWIW similar crashes also happened on 4.14 and 4.19 LTS. You may see
more info about these crashes on the dashboard bug page.

> general protection fault, probably for non-canonical address 0xf1918d9191919193: 0000 [#1] PREEMPT SMP KASAN
> KASAN: maybe wild-memory-access in range [0x8c8c8c8c8c8c8c98-0x8c8c8c8c8c8c8c9f]
> CPU: 0 PID: 933 Comm: syz-executor.0 Not tainted 5.7.0-rc1-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline]
> RIP: 0010:mm_update_next_owner+0x49b/0x7a0 kernel/exit.c:385
> Code: 48 8d bd 48 03 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 f4 02 00 00 48 8b ad 48 03 00 00 4c 8d 7d 10 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 cb 02 00 00 48 8b 45 10 48 8d a8 68 fa ff ff 49
> RSP: 0018:ffffc90018517d20 EFLAGS: 00010a07
> RAX: 1191919191919193 RBX: dffffc0000000000 RCX: ffffffff81459ed3
> RDX: 0000000000000000 RSI: ffffffff81459ee1 RDI: ffff88800013e8e0
> RBP: 8c8c8c8c8c8c8c8c R08: ffff8882123f0580 R09: fffffbfff1301219
> R10: ffffffff898090c3 R11: fffffbfff1301218 R12: ffff88809552f800
> R13: ffff88800013e1c0 R14: 0000000000000000 R15: 8c8c8c8c8c8c8c9c
> FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000400200 CR3: 000000020b913000 CR4: 00000000001426f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  exit_mm kernel/exit.c:478 [inline]
>  do_exit+0xa49/0x2dd0 kernel/exit.c:782
>  do_group_exit+0x125/0x340 kernel/exit.c:893
>  __do_sys_exit_group kernel/exit.c:904 [inline]
>  __se_sys_exit_group kernel/exit.c:902 [inline]
>  __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:902
>  do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
>  entry_SYSCALL_64_after_hwframe+0x49/0xb3
> RIP: 0033:0x45c889
> Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffd4c670f58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
> RAX: ffffffffffffffda RBX: 000000000000001e RCX: 000000000045c889
> RDX: 0000000000416421 RSI: fffffffffffffff7 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 01ffffffffffffff R09: 00007ffd4c670fb0
> R10: 00000000007702b0 R11: 0000000000000246 R12: 0000000000000001
> R13: 00007ffd4c670fb0 R14: 0000000000000000 R15: 00007ffd4c670fc0
> Modules linked in:
> ---[ end trace 30f7c81df55d5d82 ]---
> RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline]
> RIP: 0010:mm_update_next_owner+0x49b/0x7a0 kernel/exit.c:385
> Code: 48 8d bd 48 03 00 00 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 f4 02 00 00 48 8b ad 48 03 00 00 4c 8d 7d 10 4c 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 cb 02 00 00 48 8b 45 10 48 8d a8 68 fa ff ff 49
> RSP: 0018:ffffc90018517d20 EFLAGS: 00010a07
> RAX: 1191919191919193 RBX: dffffc0000000000 RCX: ffffffff81459ed3
> RDX: 0000000000000000 RSI: ffffffff81459ee1 RDI: ffff88800013e8e0
> RBP: 8c8c8c8c8c8c8c8c R08: ffff8882123f0580 R09: fffffbfff1301219
> R10: ffffffff898090c3 R11: fffffbfff1301218 R12: ffff88809552f800
> R13: ffff88800013e1c0 R14: 0000000000000000 R15: 8c8c8c8c8c8c8c9c
> FS:  0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000400200 CR3: 000000020b913000 CR4: 00000000001426f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>
>
> ---
> 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@...glegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> --
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