Date:   Thu, 5 Jul 2018 18:21:11 +0200
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     syzbot <syzbot+6cea61a6cd1e9ae6b195@...kaller.appspotmail.com>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Ingo Molnar <mingo@...hat.com>, namit@...are.com,
        Peter Zijlstra <peterz@...radead.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        tim.c.chen@...ux.intel.com,
        "the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: KASAN: stack-out-of-bounds Read in switch_mm_irqs_off

On Wed, Jul 4, 2018 at 5:11 PM, syzbot
<syzbot+6cea61a6cd1e9ae6b195@...kaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    2bdea157b999 Merge branch 'sctp-fully-support-for-dscp-and..
> git tree:       bpf-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=136a7e0c400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f62553dc846b0692
> dashboard link: https://syzkaller.appspot.com/bug?extid=6cea61a6cd1e9ae6b195
> compiler:       gcc (GCC) 8.0.1 20180413 (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+6cea61a6cd1e9ae6b195@...kaller.appspotmail.com

#syz dup: KASAN: stack-out-of-bounds Read in timerqueue_add

> ==================================================================
> BUG: KASAN: stack-out-of-bounds in switch_mm_irqs_off+0x13db/0x16c0
> arch/x86/mm/tlb.c:275
> PANIC: double fault, error_code: 0x0
> Read of size 8 at addr ffff8801957727f0 by task swapper/0/0
> CPU: 1 PID: 6433 Comm: syz-executor2 Not tainted 4.18.0-rc3+ #45
>
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.18.0-rc3+ #45
> RIP: 0010:__lock_acquire+0x2e/0x5020 kernel/locking/lockdep.c:3294
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Code:
> Call Trace:
> 41 57
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
> 41
> 89 cf
> 41 56
> 41 55
> 49 89
>  print_address_description+0x6c/0x20b mm/kasan/report.c:256
> fd
> 41
>  kasan_report_error mm/kasan/report.c:354 [inline]
>  kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
> 54
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
> 45
>  switch_mm_irqs_off+0x13db/0x16c0 arch/x86/mm/tlb.c:275
> 89 cc
> 53
> 65
> 4c
> 8b 34 25
> 40
> ee
> 01 00
> 48
> 83
> e4 f0
>  context_switch kernel/sched/core.c:2850 [inline]
>  __schedule+0x79c/0x1ed0 kernel/sched/core.c:3504
> 48 81
> ec
> 60 03
> 00
> 00
> 48
> 8b
> 45 10
> <89>
>  schedule_idle+0x45/0x80 kernel/sched/core.c:3575
> 94 24
>  do_idle+0x17f/0x570 kernel/sched/idle.c:286
> 80
> 00
> 00
>  cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368
> 00
> 48 ba
> 00
> 00
>  rest_init+0xe1/0xe4 init/main.c:442
> 00 00
>  start_kernel+0x90e/0x949 init/main.c:738
> 00
> fc
> ff df
> 48
> 89 84
> 24 98
>  x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452
>  x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433
> RSP: 0018:ffff880193f7eea0 EFLAGS: 00010086
>  secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242
> RAX: 0000000000000000 RBX: 1ffff100327efe50 RCX: 0000000000000002
>
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff88f92620
> Allocated by task 4496:
> RBP: ffff880193f7f228 R08: 0000000000000000 R09: 0000000000000000
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
> R10: ffff880195aa71b8 R11: ffff8801daf236b3 R12: 0000000000000000
>  set_track mm/kasan/kasan.c:460 [inline]
>  kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
> R13: ffffffff88f92620 R14: ffff8801aa290440 R15: 0000000000000002
>  kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
> FS:  00007f39fda9b700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
>  kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  dup_mm kernel/fork.c:1234 [inline]
>  copy_mm kernel/fork.c:1297 [inline]
>  copy_process.part.40+0x235f/0x7220 kernel/fork.c:1803
> CR2: ffff880193f7ee98 CR3: 00000001d6d6a000 CR4: 00000000001406e0
>  copy_process kernel/fork.c:1616 [inline]
>  _do_fork+0x291/0x12a0 kernel/fork.c:2099
> DR0: 00000000200001c0 DR1: 0000000020000000 DR2: 0000000000000000
>  __do_sys_clone kernel/fork.c:2206 [inline]
>  __se_sys_clone kernel/fork.c:2200 [inline]
>  __x64_sys_clone+0xbf/0x150 kernel/fork.c:2200
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
> Call Trace:
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>
>
> ---
> 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#bug-status-tracking for how to communicate with
> syzbot.
>
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