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Subject: KASAN: use-after-free Read in llc_conn_tmr_common_cb
From: syzbot <syzbot+f922284c18ea23a8e457@syzkaller.appspotmail.com>
To: davem@davemloft.net, keescook@chromium.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        syzkaller-bugs@googlegroups.com, xiyou.wangcong@gmail.com
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Hello,

syzbot hit the following crash on upstream commit
a27fc14219f2e3c4a46ba9177b04d9b52c875532 (Mon Apr 16 21:07:39 2018 +0000)
Merge branch 'parisc-4.17-3' of  
git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=f922284c18ea23a8e457

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=6056927826018304
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=-5914490758943236750
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f922284c18ea23a8e457@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

binder: 10195:10196 transaction failed 29189/-3, size 0-0 line 2963
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
binder: undelivered TRANSACTION_ERROR: 29189
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3888/0x5140  
kernel/locking/lockdep.c:3310
Read of size 8 at addr ffff8801a8c862e0 by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.17.0-rc1+ #6
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  <IRQ>
  __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_load8_noabort+0x14/0x20 mm/kasan/report.c:433
  __lock_acquire+0x3888/0x5140 kernel/locking/lockdep.c:3310
  lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920
  __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
  _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:144
  spin_lock include/linux/spinlock.h:310 [inline]
  llc_conn_tmr_common_cb+0x8d/0x9e0 net/llc/llc_c_ac.c:1328
  llc_conn_ack_tmr_cb+0x1e/0x30 net/llc/llc_c_ac.c:1357
  call_timer_fn+0x230/0x940 kernel/time/timer.c:1326
  expire_timers kernel/time/timer.c:1363 [inline]
  __run_timers+0x79e/0xc50 kernel/time/timer.c:1666
  run_timer_softirq+0x4c/0x70 kernel/time/timer.c:1692
  __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285
  invoke_softirq kernel/softirq.c:365 [inline]
  irq_exit+0x1d1/0x200 kernel/softirq.c:405
  exiting_irq arch/x86/include/asm/apic.h:525 [inline]
  smp_apic_timer_interrupt+0x17e/0x710 arch/x86/kernel/apic/apic.c:1052
  apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
  </IRQ>
RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54
RSP: 0018:ffffffff88a07bc0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 1ffffffff1140f7b RCX: 0000000000000000
RDX: 1ffffffff1163130 RSI: 0000000000000001 RDI: ffffffff88b18980
RBP: ffffffff88a07bc0 R08: ffffed003b6046c3 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff88a07c78 R14: ffffffff89591560 R15: 0000000000000000
  arch_safe_halt arch/x86/include/asm/paravirt.h:94 [inline]
  default_idle+0xc2/0x440 arch/x86/kernel/process.c:354
  arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:345
  default_idle_call+0x6d/0x90 kernel/sched/idle.c:93
  cpuidle_idle_call kernel/sched/idle.c:153 [inline]
  do_idle+0x395/0x560 kernel/sched/idle.c:262
  cpu_startup_entry+0x104/0x120 kernel/sched/idle.c:368
  rest_init+0xe1/0xe4 init/main.c:441
  start_kernel+0x906/0x92d init/main.c:737
  x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:445
  x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:426
  secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:242

Allocated by task 10136:
  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
  __do_kmalloc mm/slab.c:3718 [inline]
  __kmalloc+0x14e/0x760 mm/slab.c:3727
  kmalloc include/linux/slab.h:517 [inline]
  sk_prot_alloc+0x1ae/0x2e0 net/core/sock.c:1474
  sk_alloc+0x104/0x17b0 net/core/sock.c:1528
  llc_sk_alloc+0x35/0x4b0 net/llc/llc_conn.c:949
  llc_ui_create+0xf3/0x3e0 net/llc/af_llc.c:173
  __sock_create+0x526/0x920 net/socket.c:1285
  sock_create net/socket.c:1325 [inline]
  __sys_socket+0x100/0x250 net/socket.c:1355
  __do_sys_socket net/socket.c:1364 [inline]
  __se_sys_socket net/socket.c:1362 [inline]
  __x64_sys_socket+0x73/0xb0 net/socket.c:1362
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10215:
  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]
  kfree+0xd9/0x260 mm/slab.c:3813
  sk_prot_free net/core/sock.c:1511 [inline]
  __sk_destruct+0x772/0xa40 net/core/sock.c:1593
  sk_destruct+0x78/0x90 net/core/sock.c:1601
  __sk_free+0x22e/0x340 net/core/sock.c:1612
  sk_free+0x42/0x50 net/core/sock.c:1623
  sock_put include/net/sock.h:1664 [inline]
  llc_sk_free+0x9a/0xb0 net/llc/llc_conn.c:997
  llc_ui_release+0x154/0x220 net/llc/af_llc.c:208
  sock_release+0x96/0x1b0 net/socket.c:594
  sock_close+0x16/0x20 net/socket.c:1149
  __fput+0x34d/0x890 fs/file_table.c:209
  ____fput+0x15/0x20 fs/file_table.c:243
  task_work_run+0x1e4/0x290 kernel/task_work.c:113
  exit_task_work include/linux/task_work.h:22 [inline]
  do_exit+0x1aee/0x2730 kernel/exit.c:865
  do_group_exit+0x16f/0x430 kernel/exit.c:968
  get_signal+0x886/0x1960 kernel/signal.c:2469
  do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810
  exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162
  prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
  syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
  do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801a8c86240
  which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 160 bytes inside of
  2048-byte region [ffff8801a8c86240, ffff8801a8c86a40)
The buggy address belongs to the page:
page:ffffea0006a32180 count:1 mapcount:0 mapping:ffff8801a8c86240 index:0x0  
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801a8c86240 0000000000000000 0000000100000003
raw: ffffea0006c17920 ffffea0006bf50a0 ffff8801dac00c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801a8c86180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8801a8c86200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> ffff8801a8c86280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                        ^
  ffff8801a8c86300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801a8c86380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
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