KASAN: use-after-free Write in tls_push_record

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    13405468f49d bpfilter: don't pass O_CREAT when opening con..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=109ad82f800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8be0182d69f8d422
dashboard link: https://syzkaller.appspot.com/bug?extid=709f2810a6a05f11d4d3
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=151ec3a7800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=154d302f800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+709f2810a6a05f11d4d3@xxxxxxxxxxxxxxxxxxxxxxxxx

RDX: 00000000fffffdef RSI: 00000000200005c0 RDI: 0000000000000003
RBP: 00007ffd6ccdd780 R08: 0000000020000000 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000004
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
==================================================================
BUG: KASAN: use-after-free in tls_fill_prepend include/net/tls.h:339  
[inline]
BUG: KASAN: use-after-free in tls_push_record+0x1023/0x13e0  
net/tls/tls_sw.c:240
Write of size 1 at addr ffff8801d88d5000 by task syz-executor377/4600

CPU: 1 PID: 4600 Comm: syz-executor377 Not tainted 4.17.0-rc6+ #61
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_store1_noabort+0x17/0x20 mm/kasan/report.c:435
 tls_fill_prepend include/net/tls.h:339 [inline]
 tls_push_record+0x1023/0x13e0 net/tls/tls_sw.c:240
 tls_sw_sendmsg+0x9de/0x12b0 net/tls/tls_sw.c:484
 inet_sendmsg+0x19f/0x690 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:629 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:639
 __sys_sendto+0x3d7/0x670 net/socket.c:1789
 __do_sys_sendto net/socket.c:1801 [inline]
 __se_sys_sendto net/socket.c:1797 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1797
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4416d9
RSP: 002b:00007ffd6ccdd758 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004416d9
RDX: 00000000fffffdef RSI: 00000000200005c0 RDI: 0000000000000003
RBP: 00007ffd6ccdd780 R08: 0000000020000000 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000004
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0007623540 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffffea0007592b60 ffff8801dae2fdd8 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d88d4f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d88d4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8801d88d5000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8801d88d5080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8801d88d5100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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