KASAN: stack-out-of-bounds Read in wait_consider_task

[syzbot]

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=11662cc2400000
kernel config: https://syzkaller.appspot.com/x/.config?x=f62553dc846b0692
dashboard link: https://syzkaller.appspot.com/bug?extid=9f4eab8ef379c9cca5e1
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
CC: [ak...@linux-foundation.org ebie...@xmission.com
kees...@chromium.org linux-...@vger.kernel.org mark.r...@arm.com
mi...@kernel.org pau...@linux.vnet.ibm.com sudipm.m...@gmail.com
vi...@zeniv.linux.org.uk zhong...@huawei.com]

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+9f4eab...@syzkaller.appspotmail.com

==================================================================
PANIC: double fault, error_code: 0x0
BUG: KASAN: stack-out-of-bounds in ptrace_reparented
include/linux/ptrace.h:92 [inline]
BUG: KASAN: stack-out-of-bounds in wait_consider_task+0x3792/0x39b0
kernel/exit.c:1374
CPU: 1 PID: 17795 Comm: syz-executor6 Not tainted 4.18.0-rc3+ #45
Read of size 8 at addr ffff880192484668 by task syz-executor6/4454
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:__lock_acquire+0x2e/0x5020 kernel/locking/lockdep.c:3294

Code:
CPU: 0 PID: 4454 Comm: syz-executor6 Not tainted 4.18.0-rc3+ #45
41
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
57 41
Call Trace:
89 cf
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
41 56
41 55
49 89
fd 41
54 45
print_address_description+0x6c/0x20b mm/kasan/report.c:256
89 cc
53 65
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
4c 8b
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
34 25
ptrace_reparented include/linux/ptrace.h:92 [inline]
wait_consider_task+0x3792/0x39b0 kernel/exit.c:1374
40 ee
01 00
48 83
e4
f0 48
81 ec
60 03
00 00
48 8b
45 10
<89> 94
24 80
00 00
00 48
ba 00
do_wait_thread kernel/exit.c:1451 [inline]
do_wait+0x477/0xb80 kernel/exit.c:1522
00
00 00
00 fc
ff df
48 89
84 24
98
kernel_wait4+0x247/0x3f0 kernel/exit.c:1665
RSP: 0018:ffff880192455f70 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 1ffff1003248ac6b RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff88f92620
RBP: ffff880192456300 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: dffffc0000000000 R12: 0000000000000000
__do_sys_wait4+0x137/0x150 kernel/exit.c:1677
R13: ffffffff88f92620 R14: ffff8801ccf20540 R15: 0000000000000002
FS: 00007f45350e8700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff880192455f68 CR3: 0000000008e6a000 CR4: 00000000001406e0
DR0: 00000000200001c0 DR1: 0000000020000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:


---
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[Dmitry Vyukov]

Actually dup of upstream-reported "KASAN: stack-out-of-bounds Read in
timerqueue_add". But I will dedup them in moderation to not spam
upstream:

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

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