Re: KASAN: stack-out-of-bounds Read in rb_erase (3)

[Dmitry Vyukov <dvyukov@google.com>]

On Sat, Jul 7, 2018 at 5:09 PM, syzbot
<syzbot+52ee52c330c2fcdade39@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    29119529d8de Merge tag 'for-linus-20180706' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=16e2550c400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=2ca6c7a31d407f86
> dashboard link: https://syzkaller.appspot.com/bug?extid=52ee52c330c2fcdade39
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=1463ef48400000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10e481b2400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+52ee52c330c2fcdade39@syzkaller.appspotmail.com

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

> 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)
> ==================================================================
> BUG: KASAN: stack-out-of-bounds in ____rb_erase_color lib/rbtree.c:258
> [inline]
> BUG: KASAN: stack-out-of-bounds in rb_erase+0x19e9/0x3550 lib/rbtree.c:462
> Read of size 8 at addr ffff8801c2dd7718 by task syz-executor396/4530
>
> CPU: 1 PID: 4530 Comm: syz-executor396 Not tainted 4.18.0-rc3+ #134
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  <IRQ>
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
>  print_address_description+0x6c/0x20b mm/kasan/report.c:256
>  kasan_report_error mm/kasan/report.c:354 [inline]
>  kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
>  ____rb_erase_color lib/rbtree.c:258 [inline]
>  rb_erase+0x19e9/0x3550 lib/rbtree.c:462
>  timerqueue_del+0x86/0x150 lib/timerqueue.c:87
>  __remove_hrtimer+0xa8/0x1b0 kernel/time/hrtimer.c:984
>  __run_hrtimer kernel/time/hrtimer.c:1380 [inline]
>  __hrtimer_run_queues+0x369/0x10c0 kernel/time/hrtimer.c:1460
>  hrtimer_interrupt+0x2f3/0x750 kernel/time/hrtimer.c:1518
>  local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
>  smp_apic_timer_interrupt+0x165/0x730 arch/x86/kernel/apic/apic.c:1050
>  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
>  </IRQ>
>
> The buggy address belongs to the page:
> page:ffffea00070b75c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
> flags: 0x2fffc0000000000()
> raw: 02fffc0000000000 0000000000000000 ffffffff070b0101 0000000000000000
> raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8801c2dd7600: f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2 00 00 00 00 00
>  ffff8801c2dd7680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>
>> ffff8801c2dd7700: f1 f1 f1 f1 00 f2 f2 f2 f2 f2 f2 f2 00 f2 f2 f2
>
>                             ^
>  ffff8801c2dd7780: f2 f2 f2 f2 00 f2 f2 f2 f2 f2 f2 f2 f8 f2 f2 f2
>  ffff8801c2dd7800: f2 f2 f2 f2 00 f2 f2 f2 00 00 00 00 00 00 00 00
> ==================================================================
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
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>
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