general protection fault in smc_ioctl

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    1f7455c3912d tcp: tcp_rack_reo_wnd() can be static
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=171a1337800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b632d8e2c2ab2c1
dashboard link: https://syzkaller.appspot.com/bug?extid=e6714328fda813fc670f
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=15782d57800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=108711a7800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e6714328fda813fc670f@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
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 4559 Comm: syz-executor292 Not tainted 4.17.0-rc4+ #50
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:smc_ioctl+0x3dc/0x9f0 net/smc/af_smc.c:1499
RSP: 0018:ffff8801ad22f770 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8801ad0df7c0 RCX: ffffffff8741188f
RDX: 0000000000000004 RSI: ffffffff8741189e RDI: 0000000000000020
RBP: ffff8801ad22f9d0 R08: ffff8801ae87e6c0 R09: ffffed00363e1818
R10: ffffed00363e1818 R11: ffff8801b1f0c0c3 R12: 1ffff10035a45ef1
R13: 0000000020000080 R14: 0000000000000000 R15: 0000000000000000
FS:  00000000017b7880(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd1f18f038 CR3: 00000001ad044000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 sock_do_ioctl+0xe4/0x3e0 net/socket.c:957
 sock_ioctl+0x30d/0x680 net/socket.c:1081
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
 __do_sys_ioctl fs/ioctl.c:708 [inline]
 __se_sys_ioctl fs/ioctl.c:706 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43fca9
RSP: 002b:00007ffd1f073588 EFLAGS: 00000213 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fca9
RDX: 0000000020000080 RSI: 0000000000005411 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000213 R12: 00000000004015d0
R13: 0000000000401660 R14: 0000000000000000 R15: 0000000000000000
Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 7d 05 00 00 4c 8b b3 90 04 00 00 48  
b8 00 00 00 00 00 fc ff df 49 8d 7e 20 48 89 fa 48 c1 ea 03 <0f> b6 04 02  
84 c0 74 08 3c 03 0f 8e 47 05 00 00 45 8b 7e 20 4c
RIP: smc_ioctl+0x3dc/0x9f0 net/smc/af_smc.c:1499 RSP: ffff8801ad22f770
---[ end trace b586e1eb098f7714 ]---


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