Subject: KASAN: use-after-free Read in tipc_group_is_open

From: syzbot <[email-masked]>
Date: Mon, 15 Jan 2018 19:58:01 -0800

Hello,

syzkaller hit the following crash on  
594831a8aba3fd045c3212a3e3bb9788c77b989d
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]
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.

==================================================================
BUG: KASAN: use-after-free in tipc_group_is_open+0x3a/0x40  
net/tipc/group.c:106
Read of size 1 at addr ffff8801d89f7378 by task syzkaller275009/3704

CPU: 0 PID: 3704 Comm: syzkaller275009 Not tainted 4.15.0-rc7+ #190
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x194/0x257 lib/dump_stack.c:53
  print_address_description+0x73/0x250 mm/kasan/report.c:252
  kasan_report_error mm/kasan/report.c:351 [inline]
  kasan_report+0x25b/0x340 mm/kasan/report.c:409
  __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:427
  tipc_group_is_open+0x3a/0x40 net/tipc/group.c:106
  tipc_poll+0x364/0x4d0 net/tipc/socket.c:740
  sock_poll+0x141/0x320 net/socket.c:1111
  do_pollfd fs/select.c:822 [inline]
  do_poll fs/select.c:872 [inline]
  do_sys_poll+0x715/0x10b0 fs/select.c:966
  SYSC_poll fs/select.c:1024 [inline]
  SyS_poll+0x10d/0x450 fs/select.c:1012
  entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x446129
RSP: 002b:00007f0f2df96db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000007
RAX: ffffffffffffffda RBX: 00000000006dbc54 RCX: 0000000000446129
RDX: 0000000000007fff RSI: 000000000000000a RDI: 0000000020ef5000
RBP: 00000000006dbc50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc07e2923f R14: 00007f0f2df979c0 R15: 0000000000000007

Allocated by task 3702:
  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:551
  kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3610
  kmalloc include/linux/slab.h:499 [inline]
  kzalloc include/linux/slab.h:688 [inline]
  tipc_group_create+0x144/0x900 net/tipc/group.c:180
  tipc_sk_join net/tipc/socket.c:2762 [inline]
  tipc_setsockopt+0x274/0xce0 net/tipc/socket.c:2877
  SYSC_setsockopt net/socket.c:1823 [inline]
  SyS_setsockopt+0x189/0x360 net/socket.c:1802
  entry_SYSCALL_64_fastpath+0x23/0x9a

Freed by task 3702:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:447
  set_track mm/kasan/kasan.c:459 [inline]
  kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
  __cache_free mm/slab.c:3488 [inline]
  kfree+0xd6/0x260 mm/slab.c:3803
  tipc_group_delete+0x2c8/0x3d0 net/tipc/group.c:234
  tipc_sk_join net/tipc/socket.c:2775 [inline]
  tipc_setsockopt+0xaa9/0xce0 net/tipc/socket.c:2877
  SYSC_setsockopt net/socket.c:1823 [inline]
  SyS_setsockopt+0x189/0x360 net/socket.c:1802
  entry_SYSCALL_64_fastpath+0x23/0x9a

The buggy address belongs to the object at ffff8801d89f7300
  which belongs to the cache kmalloc-128 of size 128
The buggy address is located 120 bytes inside of
  128-byte region [ffff8801d89f7300, ffff8801d89f7380)
The buggy address belongs to the page:
page:ffffea0007627dc0 count:1 mapcount:0 mapping:ffff8801d89f7000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d89f7000 0000000000000000 0000000100000015
raw: ffffea0007622720 ffffea0007627ce0 ffff8801dac00640 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801d89f7200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
  ffff8801d89f7280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ffff8801d89f7300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                 ^
  ffff8801d89f7380: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
  ffff8801d89f7400: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
==================================================================

---
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