general protection fault in tipc_conn_delete_sub

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    919dce24 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1250d0c7e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d6a1e2f9a9986236
dashboard link: https://syzkaller.appspot.com/bug?extid=55a38037455d0351efd3
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=118ff0c7e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+55a38037455d0351efd3@xxxxxxxxxxxxxxxxxxxxxxxxx

general protection fault, probably for non-canonical address 0xdffffc0000000014: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000a0-0x00000000000000a7]
CPU: 1 PID: 113 Comm: kworker/u4:3 Not tainted 5.6.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: tipc_send tipc_conn_send_work
RIP: 0010:tipc_conn_delete_sub+0x54/0x440 net/tipc/topsrv.c:231
Code: 48 c1 ea 03 80 3c 02 00 0f 85 f0 03 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 18 48 8d bd a0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 c0 03 00 00 48 c7 c0 34 0b 8a 8a 4c 8b a5 a0 00
RSP: 0018:ffffc900012d7b58 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff8880a8269c00 RCX: ffffffff8789ca01
RDX: 0000000000000014 RSI: ffffffff8789a059 RDI: 00000000000000a0
RBP: 0000000000000000 R08: ffff8880a8d88380 R09: fffffbfff18577a8
R10: fffffbfff18577a7 R11: ffffffff8c2bbd3f R12: dffffc0000000000
R13: ffff888093d35a18 R14: ffff8880a8269c00 R15: ffff888093d35a00
FS:  0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000076c000 CR3: 000000009441d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tipc_conn_send_to_sock+0x380/0x560 net/tipc/topsrv.c:266
 tipc_conn_send_work+0x6f/0x90 net/tipc/topsrv.c:304
 process_one_work+0x965/0x16a0 kernel/workqueue.c:2266
 worker_thread+0x96/0xe20 kernel/workqueue.c:2412
 kthread+0x388/0x470 kernel/kthread.c:268
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace 2c161a84be832606 ]---
RIP: 0010:tipc_conn_delete_sub+0x54/0x440 net/tipc/topsrv.c:231
Code: 48 c1 ea 03 80 3c 02 00 0f 85 f0 03 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 18 48 8d bd a0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 c0 03 00 00 48 c7 c0 34 0b 8a 8a 4c 8b a5 a0 00
RSP: 0018:ffffc900012d7b58 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff8880a8269c00 RCX: ffffffff8789ca01
RDX: 0000000000000014 RSI: ffffffff8789a059 RDI: 00000000000000a0
RBP: 0000000000000000 R08: ffff8880a8d88380 R09: fffffbfff18577a8
R10: fffffbfff18577a7 R11: ffffffff8c2bbd3f R12: dffffc0000000000
R13: ffff888093d35a18 R14: ffff8880a8269c00 R15: ffff888093d35a00
FS:  0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020800000 CR3: 0000000091b8e000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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