Date:   Thu, 17 May 2018 10:57:02 -0700
From:   syzbot <syzbot+5d47e9ec91a6f15dbd6f@...kaller.appspotmail.com>
To:     alexey.kodanev@...cle.com, davem@...emloft.net,
        dccp@...r.kernel.org, edumazet@...gle.com, gerrit@....abdn.ac.uk,
        keescook@...omium.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, soheil@...gle.com,
        syzkaller-bugs@...glegroups.com
Subject: KASAN: use-after-free Read in timer_is_static_object

Hello,

syzbot found the following crash on:

HEAD commit:    e6506eb24187 Merge tag 'trace-v4.17-rc4-2' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=177fe477800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3b4e30da84ec1ed
dashboard link: https://syzkaller.appspot.com/bug?extid=5d47e9ec91a6f15dbd6f
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+5d47e9ec91a6f15dbd6f@...kaller.appspotmail.com

RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000016
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000017
R13: 0000000000000053 R14: 00000000006f4868 R15: 0000000000000001
==================================================================
BUG: KASAN: use-after-free in timer_is_static_object+0x80/0x90  
kernel/time/timer.c:607
Read of size 8 at addr ffff8801bebb5118 by task syz-executor2/25299

CPU: 1 PID: 25299 Comm: syz-executor2 Not tainted 4.17.0-rc5+ #54
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
  timer_is_static_object+0x80/0x90 kernel/time/timer.c:607
  debug_object_activate+0x2d9/0x670 lib/debugobjects.c:508
  debug_timer_activate kernel/time/timer.c:709 [inline]
  debug_activate kernel/time/timer.c:764 [inline]
  __mod_timer kernel/time/timer.c:1041 [inline]
  mod_timer+0x4d3/0x13b0 kernel/time/timer.c:1102
  sk_reset_timer+0x22/0x60 net/core/sock.c:2742
  ccid2_hc_tx_rto_expire+0x587/0x680 net/dccp/ccids/ccid2.c:147
  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:cap_capable+0x3f/0x260 security/commoncap.c:82
RSP: 0018:ffff8801ac75f8c8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: ffffffff88d5be00 RCX: 0000000000000000
RDX: 1ffff100386dc571 RSI: ffffffff830ee893 RDI: ffff8801c36e2b88
RBP: ffff8801ac75f910 R08: ffff8801ac126440 R09: ffff8801ac75fcb8
R10: ffff8801ac126c78 R11: ffff8801ac75fc78 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8801c36e2b00 R15: 0000000000000021
  cap_vm_enough_memory+0x50/0x70 security/commoncap.c:1307
  security_vm_enough_memory_mm+0x71/0xc0 security/security.c:327
  mmap_region+0x37b/0x1870 mm/mmap.c:1714
  do_mmap+0xde2/0x1360 mm/mmap.c:1535
  do_mmap_pgoff include/linux/mm.h:2237 [inline]
  vm_mmap_pgoff+0x1fb/0x2a0 mm/util.c:357
  ksys_mmap_pgoff+0x26e/0x640 mm/mmap.c:1585
  __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
  __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
  __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455a5a
RSP: 002b:0000000000a3e778 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000455a5a
RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000
RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000

Allocated by task 25374:
  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
  ccid_new+0x25b/0x3e0 net/dccp/ccid.c:151
  dccp_hdlr_ccid+0x27/0x150 net/dccp/feat.c:44
  __dccp_feat_activate+0x184/0x270 net/dccp/feat.c:344
  dccp_feat_activate_values+0x3a7/0x819 net/dccp/feat.c:1538
  dccp_create_openreq_child+0x472/0x610 net/dccp/minisocks.c:128
  dccp_v4_request_recv_sock+0x12c/0xca0 net/dccp/ipv4.c:408
  dccp_v6_request_recv_sock+0x125d/0x1f10 net/dccp/ipv6.c:415
  dccp_check_req+0x455/0x6a0 net/dccp/minisocks.c:197
  dccp_v4_rcv+0x7b8/0x1f3f net/dccp/ipv4.c:841
  ip_local_deliver_finish+0x2e3/0xd80 net/ipv4/ip_input.c:215
  NF_HOOK include/linux/netfilter.h:288 [inline]
  ip_local_deliver+0x1e1/0x720 net/ipv4/ip_input.c:256
  dst_input include/net/dst.h:450 [inline]
  ip_rcv_finish+0x81b/0x2200 net/ipv4/ip_input.c:396
  NF_HOOK include/linux/netfilter.h:288 [inline]
  ip_rcv+0xb70/0x143d net/ipv4/ip_input.c:492
  __netif_receive_skb_core+0x26f5/0x3630 net/core/dev.c:4592
  __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:4657
  process_backlog+0x219/0x760 net/core/dev.c:5337
  napi_poll net/core/dev.c:5735 [inline]
  net_rx_action+0x7b7/0x1930 net/core/dev.c:5801
  __do_softirq+0x2e0/0xaf5 kernel/softirq.c:285

Freed by task 25374:
  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
  ccid_hc_tx_delete+0xc3/0x100 net/dccp/ccid.c:190
  dccp_disconnect+0x130/0xc66 net/dccp/proto.c:286
  dccp_close+0x3bc/0xe60 net/dccp/proto.c:1045
  inet_release+0x104/0x1f0 net/ipv4/af_inet.c:427
  inet6_release+0x50/0x70 net/ipv6/af_inet6.c:460
  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
  tracehook_notify_resume include/linux/tracehook.h:191 [inline]
  exit_to_usermode_loop+0x2bd/0x310 arch/x86/entry/common.c:166
  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 ffff8801bebb4cc0
  which belongs to the cache ccid2_hc_tx_sock of size 1240
The buggy address is located 1112 bytes inside of
  1240-byte region [ffff8801bebb4cc0, ffff8801bebb5198)
The buggy address belongs to the page:
page:ffffea0006faed00 count:1 mapcount:0 mapping:ffff8801bebb41c0  
index:0xffff8801bebb5240 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801bebb41c0 ffff8801bebb5240 0000000100000003
raw: ffff8801cdba3138 ffffea0007634120 ffff8801cdbaab40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801bebb5000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801bebb5080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801bebb5100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                             ^
  ffff8801bebb5180: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8801bebb5200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================


---
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