Subject: KASAN: use-after-free Read in timer_is_static_object (2)

From: syzbot <[email-masked]>
Date: Tue, 14 May 2019 22:28:04 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    63863ee8 Merge tag 'gcc-plugins-v5.2-rc1' of ssh://gitolit..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=128b8d74a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=52ff73a1f6d0b441
dashboard link: https://syzkaller.appspot.com/bug?extid=81215bf96c82318c7e74
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: [email-masked]

==================================================================
BUG: KASAN: use-after-free in timer_is_static_object+0x80/0x90  
kernel/time/timer.c:608
Read of size 8 at addr ffff8880a5e88da8 by task kworker/0:2/2851

CPU: 0 PID: 2851 Comm: kworker/0:2 Not tainted 5.1.0+ #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: pencrypt padata_serial_worker
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x172/0x1f0 lib/dump_stack.c:113
  print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
  __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
  kasan_report+0x12/0x20 mm/kasan/common.c:614
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
  timer_is_static_object+0x80/0x90 kernel/time/timer.c:608
  debug_object_activate+0x298/0x4f0 lib/debugobjects.c:510
  debug_timer_activate kernel/time/timer.c:710 [inline]
  __mod_timer kernel/time/timer.c:1035 [inline]
  mod_timer kernel/time/timer.c:1096 [inline]
  add_timer+0x3c6/0x930 kernel/time/timer.c:1132
  __queue_delayed_work+0x1af/0x270 kernel/workqueue.c:1648
  queue_delayed_work_on+0x19a/0x200 kernel/workqueue.c:1673
  queue_delayed_work include/linux/workqueue.h:509 [inline]
  schedule_delayed_work include/linux/workqueue.h:610 [inline]
  tls_encrypt_done+0x44c/0x560 net/tls/tls_sw.c:477
  aead_request_complete include/crypto/internal/aead.h:75 [inline]
  pcrypt_aead_serial+0x7f/0xb0 crypto/pcrypt.c:123
  padata_serial_worker+0x2a8/0x4b0 kernel/padata.c:349
  process_one_work+0x98e/0x1790 kernel/workqueue.c:2268
  worker_thread+0x98/0xe40 kernel/workqueue.c:2414
  kthread+0x357/0x430 kernel/kthread.c:253
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Allocated by task 9310:
  save_stack+0x23/0x90 mm/kasan/common.c:71
  set_track mm/kasan/common.c:79 [inline]
  __kasan_kmalloc mm/kasan/common.c:489 [inline]
  __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
  kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
  kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3586
  kmalloc include/linux/slab.h:547 [inline]
  kzalloc include/linux/slab.h:742 [inline]
  tls_set_sw_offload+0x123e/0x1640 net/tls/tls_sw.c:2193
  do_tls_setsockopt_conf net/tls/tls_main.c:527 [inline]
  do_tls_setsockopt net/tls/tls_main.c:574 [inline]
  tls_setsockopt+0x7cd/0x8d0 net/tls/tls_main.c:593
  sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3130
  __sys_setsockopt+0x180/0x280 net/socket.c:2078
  __do_sys_setsockopt net/socket.c:2089 [inline]
  __se_sys_setsockopt net/socket.c:2086 [inline]
  __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2086
  do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9303:
  save_stack+0x23/0x90 mm/kasan/common.c:71
  set_track mm/kasan/common.c:79 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/common.c:451
  kasan_slab_free+0xe/0x10 mm/kasan/common.c:459
  __cache_free mm/slab.c:3463 [inline]
  kfree+0xcf/0x230 mm/slab.c:3786
  tls_sw_free_resources_tx+0x3b3/0x6e0 net/tls/tls_sw.c:2100
  tls_sk_proto_close+0x5fa/0x780 net/tls/tls_main.c:289
  inet_release+0x105/0x1f0 net/ipv4/af_inet.c:432
  inet6_release+0x53/0x80 net/ipv6/af_inet6.c:474
  __sock_release+0xd3/0x2b0 net/socket.c:607
  sock_close+0x1b/0x30 net/socket.c:1279
  __fput+0x302/0x890 fs/file_table.c:279
  ____fput+0x16/0x20 fs/file_table.c:312
  task_work_run+0x14a/0x1c0 kernel/task_work.c:113
  tracehook_notify_resume include/linux/tracehook.h:188 [inline]
  exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:167
  prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:276 [inline]
  do_syscall_64+0x57e/0x670 arch/x86/entry/common.c:301
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a5e88d00
  which belongs to the cache kmalloc-512 of size 512
The buggy address is located 168 bytes inside of
  512-byte region [ffff8880a5e88d00, ffff8880a5e88f00)
The buggy address belongs to the page:
page:ffffea000297a200 count:1 mapcount:0 mapping:ffff8880aa400940 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00012ac408 ffffea0002947608 ffff8880aa400940
raw: 0000000000000000 ffff8880a5e88080 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8880a5e88c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8880a5e88d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8880a5e88d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                   ^
  ffff8880a5e88e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8880a5e88e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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