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

[syzbot]

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@xxxxxxxxxxxxxxxxxxxxxxxxx

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
==================================================================


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