general protection fault in smap_list_hash_remove

[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=102e5b48400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f62553dc846b0692
dashboard link: https://syzkaller.appspot.com/bug?extid=b912ba691bb508925d72
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=168d1662400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1556a594400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b912ba691bb508925d72@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)
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
CPU: 0 PID: 4454 Comm: syz-executor594 Not tainted 4.18.0-rc3+ #45
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:do_raw_spin_lock+0x27/0x200 kernel/locking/spinlock_debug.c:111
Code: 00 00 00 48 b8 00 00 00 00 00 fc ff df 55 48 89 e5 41 56 41 55 41 54  
53 48 89 fb 48 83 c7 04 48 89 fa 48 c1 ea 03 48 83 ec 08 <0f> b6 14 02 48  
89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 7b
RSP: 0018:ffff8801ad3e77c8 EFLAGS: 00010292
RAX: dffffc0000000000 RBX: 0000000000000230 RCX: 0000000000000000
RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000234
RBP: ffff8801ad3e77f0 R08: 0000000000000001 R09: 0000000000000000
R10: ffffed00359b8286 R11: ffff8801acdc1433 R12: dffffc0000000000
R13: ffff8801d8b35540 R14: ffff8801c65bb118 R15: ffff8801c65bb100
FS:  00007f51a93fb700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc4338af60 CR3: 00000001ad3f7000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:136 [inline]
 _raw_spin_lock_bh+0x39/0x40 kernel/locking/spinlock.c:168
 spin_lock_bh include/linux/spinlock.h:315 [inline]
 smap_list_hash_remove+0xa3/0x470 kernel/bpf/sockmap.c:1683
 sock_hash_ctx_update_elem.isra.27+0x1140/0x1690 kernel/bpf/sockmap.c:2384
 sock_hash_update_elem+0x157/0x2f0 kernel/bpf/sockmap.c:2418
 map_update_elem+0x5c4/0xc90 kernel/bpf/syscall.c:765
 __do_sys_bpf kernel/bpf/syscall.c:2296 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:2267 [inline]
 __x64_sys_bpf+0x32d/0x510 kernel/bpf/syscall.c:2267
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x445d19
Code: e8 2c b7 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 2b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f51a93face8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00000000006dac3c RCX: 0000000000445d19
RDX: 0000000000000020 RSI: 0000000020000180 RDI: 0000000000000002
RBP: 00000000006dac38 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd36a1e17f R14: 00007f51a93fb9c0 R15: 0000000000000005
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace 996d9c1f5fab271a ]---
RIP: 0010:do_raw_spin_lock+0x27/0x200 kernel/locking/spinlock_debug.c:111
Code: 00 00 00 48 b8 00 00 00 00 00 fc ff df 55 48 89 e5 41 56 41 55 41 54  
53 48 89 fb 48 83 c7 04 48 89 fa 48 c1 ea 03 48 83 ec 08 <0f> b6 14 02 48  
89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 7b
RSP: 0018:ffff8801ad3e77c8 EFLAGS: 00010292
RAX: dffffc0000000000 RBX: 0000000000000230 RCX: 0000000000000000
RDX: 0000000000000046 RSI: 0000000000000000 RDI: 0000000000000234
RBP: ffff8801ad3e77f0 R08: 0000000000000001 R09: 0000000000000000
R10: ffffed00359b8286 R11: ffff8801acdc1433 R12: dffffc0000000000
R13: ffff8801d8b35540 R14: ffff8801c65bb118 R15: ffff8801c65bb100
FS:  00007f51a93fb700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc4338af60 CR3: 00000001ad3f7000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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