general protection fault in tls_trim_both_msgs

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    9e6dfe80 Add linux-next specific files for 20190724
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1046971fa00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6cbb8fc2cf2842d7
dashboard link: https://syzkaller.appspot.com/bug?extid=0e0fedcad708d12d3032
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+0e0fedcad708d12d3032@xxxxxxxxxxxxxxxxxxxxxxxxx

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: 15517 Comm: syz-executor.4 Not tainted 5.3.0-rc1-next-20190724  
#50
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:tls_trim_both_msgs+0x54/0x130 net/tls/tls_sw.c:268
Code: 48 c1 ea 03 80 3c 02 00 0f 85 e3 00 00 00 4d 8b b5 b0 06 00 00 48 b8  
00 00 00 00 00 fc ff df 49 8d 7e 28 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 b3 00 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b
RSP: 0018:ffff8880612cfac0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff8880a8794340 RCX: ffffc9000e7b9000
RDX: 0000000000000005 RSI: ffffffff86298656 RDI: 0000000000000028
RBP: ffff8880612cfae0 R08: ffff88805ae4c580 R09: fffffbfff14a8155
R10: fffffbfff14a8154 R11: ffffffff8a540aa7 R12: 0000000000000000
R13: ffff888061d82e00 R14: 0000000000000000 R15: 00000000ffffffe0
FS:  00007f7d33516700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2fa2f000 CR3: 000000009fcf1000 CR4: 00000000001406e0
Call Trace:
 tls_sw_sendmsg+0xe38/0x17b0 net/tls/tls_sw.c:1057
 inet6_sendmsg+0x9e/0xe0 net/ipv6/af_inet6.c:576
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:657
 __sys_sendto+0x262/0x380 net/socket.c:1952
 __do_sys_sendto net/socket.c:1964 [inline]
 __se_sys_sendto net/socket.c:1960 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1960
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459829
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7d33515c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000459829
RDX: ffffffffffffffc1 RSI: 00000000200005c0 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 1201000000003618
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7d335166d4
R13: 00000000004c7669 R14: 00000000004dcc70 R15: 00000000ffffffff
Modules linked in:
---[ end trace 2dd728cceb39a185 ]---
RIP: 0010:tls_trim_both_msgs+0x54/0x130 net/tls/tls_sw.c:268
Code: 48 c1 ea 03 80 3c 02 00 0f 85 e3 00 00 00 4d 8b b5 b0 06 00 00 48 b8  
00 00 00 00 00 fc ff df 49 8d 7e 28 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 b3 00 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b
RSP: 0018:ffff8880612cfac0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff8880a8794340 RCX: ffffc9000e7b9000
RDX: 0000000000000005 RSI: ffffffff86298656 RDI: 0000000000000028
RBP: ffff8880612cfae0 R08: ffff88805ae4c580 R09: fffffbfff14a8155
R10: fffffbfff14a8154 R11: ffffffff8a540aa7 R12: 0000000000000000
R13: ffff888061d82e00 R14: 0000000000000000 R15: 00000000ffffffe0
FS:  00007f7d33516700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000019dbe80 CR3: 000000009fcf1000 CR4: 00000000001406e0


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