Message-ID: <001a1140e0de4345b30566e8c8dd@google.com>
Date:   Thu, 08 Mar 2018 08:01:01 -0800
From:   syzbot <syzbot+e79dce0b0dcbedb7d425@...kaller.appspotmail.com>
To:     davem@...emloft.net, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, netdev@...r.kernel.org,
        rds-devel@....oracle.com, santosh.shilimkar@...cle.com,
        syzkaller-bugs@...glegroups.com
Subject: KASAN: use-after-free Read in rds_tcp_tune (2)

Hello,

syzbot hit the following crash on upstream commit
86f84779d8e92a690b2f281175ea06b884cb6fa4 (Tue Mar 6 20:41:30 2018 +0000)
Merge branch 'siginfo-linus' of  
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.

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Reported-by: syzbot+e79dce0b0dcbedb7d425@...kaller.appspotmail.com
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details.
If you forward the report, please keep this part and the footer.

binder: undelivered TRANSACTION_COMPLETE
binder: send failed reply for transaction 14, target dead
bond0 (unregistering): Released all slaves
==================================================================
IPVS: ftp: loaded support on port[0] = 21
BUG: KASAN: use-after-free in rds_tcp_tune+0x491/0x520 net/rds/tcp.c:414
Read of size 4 at addr ffff8801b0bf43d8 by task kworker/u4:0/5

CPU: 0 PID: 5 Comm: kworker/u4:0 Not tainted 4.16.0-rc4+ #344
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: krdsd rds_connect_worker
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x24d lib/dump_stack.c:53
  print_address_description+0x73/0x250 mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report+0x23c/0x360 mm/kasan/report.c:412
  __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
  rds_tcp_tune+0x491/0x520 net/rds/tcp.c:414
  rds_tcp_conn_path_connect+0x397/0x940 net/rds/tcp_connect.c:113
  rds_connect_worker+0x156/0x1f0 net/rds/threads.c:175
  process_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113
  worker_thread+0x223/0x1990 kernel/workqueue.c:2247
  kthread+0x33c/0x400 kernel/kthread.c:238
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406

Allocated by task 4279:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
  set_track mm/kasan/kasan.c:459 [inline]
  kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
  __do_kmalloc mm/slab.c:3705 [inline]
  __kmalloc+0x162/0x760 mm/slab.c:3714
  kmalloc include/linux/slab.h:517 [inline]
  kzalloc include/linux/slab.h:701 [inline]
  ops_init+0x172/0x570 net/core/net_namespace.c:108
  setup_net+0x351/0x760 net/core/net_namespace.c:302
  copy_net_ns+0x238/0x580 net/core/net_namespace.c:426
  create_new_namespaces+0x425/0x880 kernel/nsproxy.c:107
  unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206
  SYSC_unshare kernel/fork.c:2407 [inline]
  SyS_unshare+0x653/0xfa0 kernel/fork.c:2357
  do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 1692:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
  set_track mm/kasan/kasan.c:459 [inline]
  __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
  __cache_free mm/slab.c:3485 [inline]
  kfree+0xd9/0x260 mm/slab.c:3800
  ops_free net/core/net_namespace.c:132 [inline]
  ops_free_list.part.8+0x27e/0x3e0 net/core/net_namespace.c:154
  ops_free_list net/core/net_namespace.c:152 [inline]
  cleanup_net+0x73f/0xcb0 net/core/net_namespace.c:521
  process_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113
  worker_thread+0x223/0x1990 kernel/workqueue.c:2247
  kthread+0x33c/0x400 kernel/kthread.c:238
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406

The buggy address belongs to the object at ffff8801b0bf4380
  which belongs to the cache kmalloc-96 of size 96
The buggy address is located 88 bytes inside of
  96-byte region [ffff8801b0bf4380, ffff8801b0bf43e0)
The buggy address belongs to the page:
page:ffffea0006c2fd00 count:1 mapcount:0 mapping:ffff8801b0bf4000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801b0bf4000 0000000000000000 0000000100000020
raw: ffffea00076bcf60 ffffea000739a320 ffff8801dac004c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801b0bf4280: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
  ffff8801b0bf4300: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
> ffff8801b0bf4380: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                                     ^
  ffff8801b0bf4400: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
  ffff8801b0bf4480: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================


---
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