KASAN: slab-out-of-bounds Write in tls_push_record (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    44960f2a7b63 staging: ashmem: Fix SIGBUS crash when traver..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10f7ea72400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2dc0cd7c2eefb46f
dashboard link: https://syzkaller.appspot.com/bug?extid=3d650eba9d63b8de7478
compiler:       gcc (GCC) 8.0.1 20180413 (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+3d650eba9d63b8de7478@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: slab-out-of-bounds in tls_fill_prepend include/net/tls.h:339  
[inline]
BUG: KASAN: slab-out-of-bounds in tls_push_record+0x1091/0x1400  
net/tls/tls_sw.c:239
Write of size 1 at addr ffff88019c5d8000 by task syz-executor2/11760

CPU: 0 PID: 11760 Comm: syz-executor2 Not tainted 4.18.0-rc7+ #172
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+0x1c9/0x2b4 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+0x1091/0x1400 net/tls/tls_sw.c:239
 tls_sw_push_pending_record+0x22/0x30 net/tls/tls_sw.c:276
 tls_handle_open_record net/tls/tls_main.c:164 [inline]
 tls_sk_proto_close+0x74c/0xae0 net/tls/tls_main.c:264
 inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427
 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:459
 __sock_release+0xd7/0x260 net/socket.c:600
 sock_close+0x19/0x20 net/socket.c:1151
 __fput+0x355/0x8b0 fs/file_table.c:209
 ____fput+0x15/0x20 fs/file_table.c:243
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:192 [inline]
 exit_to_usermode_loop+0x313/0x370 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4105c1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 19 00 00 c3 48  
83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48  
89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:0000000000a3feb0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000014 RCX: 00000000004105c1
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000013
RBP: 0000000000000010 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000a3fde0 R11: 0000000000000293 R12: 0000000000000000
R13: 000000000002fd87 R14: 0000000000000094 R15: badc0ffeebadface

Allocated by task 2597:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3554
 getname_flags+0xd0/0x5a0 fs/namei.c:140
 user_path_at_empty+0x2d/0x50 fs/namei.c:2584
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0x129/0x210 fs/stat.c:185
 vfs_stat include/linux/fs.h:3102 [inline]
 __do_sys_newstat+0x8f/0x110 fs/stat.c:337
 __se_sys_newstat fs/stat.c:333 [inline]
 __x64_sys_newstat+0x54/0x80 fs/stat.c:333
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2597:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x86/0x2d0 mm/slab.c:3756
 putname+0xf2/0x130 fs/namei.c:261
 filename_lookup+0x397/0x510 fs/namei.c:2330
 user_path_at_empty+0x40/0x50 fs/namei.c:2584
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0x129/0x210 fs/stat.c:185
 vfs_stat include/linux/fs.h:3102 [inline]
 __do_sys_newstat+0x8f/0x110 fs/stat.c:337
 __se_sys_newstat fs/stat.c:333 [inline]
 __x64_sys_newstat+0x54/0x80 fs/stat.c:333
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88019c5d8980
 which belongs to the cache names_cache of size 4096
The buggy address is located 2432 bytes to the left of
 4096-byte region [ffff88019c5d8980, ffff88019c5d9980)
The buggy address belongs to the page:
page:ffffea0006717600 count:1 mapcount:0 mapping:ffff8801dad85dc0 index:0x0  
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea0006470d88 ffffea0006717688 ffff8801dad85dc0
raw: 0000000000000000 ffff88019c5d8980 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88019c5d7f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88019c5d7f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff88019c5d8000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff88019c5d8080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88019c5d8100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
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#bug-status-tracking for how to communicate with  
syzbot.