general protection fault in wait_consider_task

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: d573e8a7 Linux 4.19.75
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12aa3241600000
kernel config: https://syzkaller.appspot.com/x/.config?x=50b385e67c7b7cdf
dashboard link: https://syzkaller.appspot.com/bug?extid=c606e4aa40937cc76853
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14322b8d600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b354e5600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c606e4...@syzkaller.appspotmail.com

audit: type=1400 audit(1569205520.150:36): avc: denied { map } for
pid=7638 comm="syz-executor420" path="/root/syz-executor420867751"
dev="sda1" ino=16483 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 7636 Comm: sshd Not tainted 4.19.75 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:wait_task_zombie kernel/exit.c:1058 [inline]
RIP: 0010:wait_consider_task+0x140b/0x3910 kernel/exit.c:1391
Code: e0 74 49 87 c6 05 0a fc f7 07 01 e8 d6 f5 12 00 e8 fa 8d 2b 00 48 8d
7b 14 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48
89 f8 83 e0 07 83 c0 03 38 d0 7c 09 84 d2 74 05 e8
RSP: 0018:ffff88808670faa0 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff813fd453
RDX: 0000000000000002 RSI: ffffffff813fd486 RDI: 0000000000000014
RBP: ffff88808670fbc8 R08: ffff888099a14440 R09: ffffed1015d24733
R10: ffffed1015d24732 R11: ffff8880ae923993 R12: 0000000000001dd6
R13: ffff88808670fcbc R14: ffff888085116480 R15: ffff88808670fcb8
FS: 00007f0e00e137c0(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000000a924e000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
do_wait_thread kernel/exit.c:1454 [inline]
do_wait+0x439/0x9d0 kernel/exit.c:1525
kernel_wait4+0x171/0x290 kernel/exit.c:1668
__do_sys_wait4+0x147/0x160 kernel/exit.c:1680
__se_sys_wait4 kernel/exit.c:1676 [inline]
__x64_sys_wait4+0x97/0xf0 kernel/exit.c:1676
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f0dff189a3e
Code: 90 90 90 90 90 90 90 90 90 90 90 90 48 83 ec 28 8b 05 c2 eb 2d 00 85
c0 75 1d 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff
ff 77 55 48 83 c4 28 c3 89 54 24 08 48 89 74 24 10
RSP: 002b:00007ffc5700af00 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0dff189a3e
RDX: 0000000000000001 RSI: 00007ffc5700af3c RDI: ffffffffffffffff
RBP: 000056367f8c5c88 R08: 00007ffc5700b000 R09: 0101010101010101
R10: 0000000000000000 R11: 0000000000000246 R12: 0000563680d3cc00
R13: 000056367f8c3fb4 R14: 0000000000000028 R15: 000056367f8c5ca0
Modules linked in:
---[ end trace ea671b9f8987e6ef ]---
RIP: 0010:wait_task_zombie kernel/exit.c:1058 [inline]
RIP: 0010:wait_consider_task+0x140b/0x3910 kernel/exit.c:1391
Code: e0 74 49 87 c6 05 0a fc f7 07 01 e8 d6 f5 12 00 e8 fa 8d 2b 00 48 8d
7b 14 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48
89 f8 83 e0 07 83 c0 03 38 d0 7c 09 84 d2 74 05 e8
RSP: 0018:ffff88808670faa0 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff813fd453
RDX: 0000000000000002 RSI: ffffffff813fd486 RDI: 0000000000000014
RBP: ffff88808670fbc8 R08: ffff888099a14440 R09: ffffed1015d24733
R10: ffffed1015d24732 R11: ffff8880ae923993 R12: 0000000000001dd6
R13: ffff88808670fcbc R14: ffff888085116480 R15: ffff88808670fcb8
FS: 00007f0e00e137c0(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffff600400 CR3: 00000000a924e000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[syzbot]

syzbot suspects this bug was fixed by commit:

commit 4eb92a1148342af1d6f82018d20cd862e1d3ab7e
Author: Leon Romanovsky <leo...@mellanox.com>
Date: Thu Oct 11 19:10:10 2018 +0000

RDMA/restrack: Protect from reentry to resource return path

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13c1a1eae00000
start commit: d573e8a7 Linux 4.19.75
git tree: linux-4.19.y

kernel config: https://syzkaller.appspot.com/x/.config?x=50b385e67c7b7cdf
dashboard link: https://syzkaller.appspot.com/bug?extid=c606e4aa40937cc76853

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14322b8d600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14b354e5600000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: RDMA/restrack: Protect from reentry to resource return path

For information about bisection process see: https://goo.gl/tpsmEJ#bisection