general protection fault in l2cap_sock_getsockopt

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    c25a951c Add linux-next specific files for 20200217
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=171b1a29e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c727d8fc485ff049
dashboard link: https://syzkaller.appspot.com/bug?extid=6446a589a5ca34dd6e8b
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10465579e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16dabb11e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+6446a589a5ca34dd6e8b@xxxxxxxxxxxxxxxxxxxxxxxxx

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 9844 Comm: syz-executor679 Not tainted 5.6.0-rc2-next-20200217-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:l2cap_sock_getsockopt+0x7d3/0x1200 net/bluetooth/l2cap_sock.c:613
Code: 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 a0 09 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 1f 48 89 da 48 c1 ea 03 <80> 3c 02 00 0f 85 75 09 00 00 48 8b 3b e8 cb be f6 ff be 67 02 00
RSP: 0018:ffffc900062f7d20 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff87253e8c
RDX: 0000000000000000 RSI: ffffffff87253f44 RDI: 0000000000000001
RBP: ffffc900062f7e00 R08: ffff88808a5001c0 R09: fffffbfff16a3f80
R10: fffffbfff16a3f7f R11: ffffffff8b51fbff R12: 0000000000000000
R13: 1ffff92000c5efa7 R14: ffff8880a9a79000 R15: ffff8880a1d92000
FS:  0000000001ccd880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000140 CR3: 0000000097113000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __sys_getsockopt+0x16d/0x310 net/socket.c:2175
 __do_sys_getsockopt net/socket.c:2190 [inline]
 __se_sys_getsockopt net/socket.c:2187 [inline]
 __x64_sys_getsockopt+0xbe/0x150 net/socket.c:2187
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x440149
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcb256f088 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440149
RDX: 000000000000000e RSI: 0000000000000112 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000020000140 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004019d0
R13: 0000000000401a60 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 63f0b6416dbaab7d ]---
RIP: 0010:l2cap_sock_getsockopt+0x7d3/0x1200 net/bluetooth/l2cap_sock.c:613
Code: 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 a0 09 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 1f 48 89 da 48 c1 ea 03 <80> 3c 02 00 0f 85 75 09 00 00 48 8b 3b e8 cb be f6 ff be 67 02 00
RSP: 0018:ffffc900062f7d20 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff87253e8c
RDX: 0000000000000000 RSI: ffffffff87253f44 RDI: 0000000000000001
RBP: ffffc900062f7e00 R08: ffff88808a5001c0 R09: fffffbfff16a3f80
R10: fffffbfff16a3f7f R11: ffffffff8b51fbff R12: 0000000000000000
R13: 1ffff92000c5efa7 R14: ffff8880a9a79000 R15: ffff8880a1d92000
FS:  0000000001ccd880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000140 CR3: 0000000097113000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches