KASAN: use-after-free Read in tipc_group_cong

[syzbot <syzbot+9845fed98688e01f431e@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    f5d582777bcb Merge branch 'for-linus' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1705d525400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c8970c89a0efbb23
dashboard link: https://syzkaller.appspot.com/bug?extid=9845fed98688e01f431e
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=101b6ba3400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+9845fed98688e01f431e@syzkaller.appspotmail.com

8021q: adding VLAN 0 to HW filter on device team0
8021q: adding VLAN 0 to HW filter on device team0
audit: type=1400 audit(1544592509.246:38): avc:  denied  { associate } for   
pid=6204 comm="syz-executor5" name="syz5"  
scontext=unconfined_u:object_r:unlabeled_t:s0  
tcontext=system_u:object_r:unlabeled_t:s0 tclass=filesystem permissive=1
==================================================================
BUG: KASAN: use-after-free in tipc_group_find_dest net/tipc/group.c:255  
[inline]
BUG: KASAN: use-after-free in tipc_group_cong+0x566/0x5d0  
net/tipc/group.c:416
Read of size 8 at addr ffff8881c59f5000 by task syz-executor4/10565

CPU: 1 PID: 10565 Comm: syz-executor4 Not tainted 4.20.0-rc6+ #151
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x244/0x39d lib/dump_stack.c:113
  print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
  tipc_group_find_dest net/tipc/group.c:255 [inline]
  tipc_group_cong+0x566/0x5d0 net/tipc/group.c:416
  tipc_send_group_anycast+0x9bb/0xc80 net/tipc/socket.c:972
  __tipc_sendmsg+0x12b1/0x1d40 net/tipc/socket.c:1309
  tipc_sendmsg+0x50/0x70 net/tipc/socket.c:1272
  sock_sendmsg_nosec net/socket.c:621 [inline]
  sock_sendmsg+0xd5/0x120 net/socket.c:631
  ___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
  __sys_sendmsg+0x11d/0x280 net/socket.c:2154
  __do_sys_sendmsg net/socket.c:2163 [inline]
  __se_sys_sendmsg net/socket.c:2161 [inline]
  __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457679
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f813d748c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457679
RDX: 0000000000000000 RSI: 00000000200006c0 RDI: 0000000000000005
RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f813d7496d4
R13: 00000000004c44dd R14: 00000000004d74c8 R15: 00000000ffffffff

Allocated by task 10551:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
  kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
  kmalloc include/linux/slab.h:546 [inline]
  kzalloc include/linux/slab.h:741 [inline]
  tipc_group_create+0x152/0xa70 net/tipc/group.c:171
  tipc_sk_join net/tipc/socket.c:2829 [inline]
  tipc_setsockopt+0x2d1/0xd70 net/tipc/socket.c:2944
  __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
  __do_sys_setsockopt net/socket.c:1913 [inline]
  __se_sys_setsockopt net/socket.c:1910 [inline]
  __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 10567:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
  __cache_free mm/slab.c:3498 [inline]
  kfree+0xcf/0x230 mm/slab.c:3817
  tipc_group_delete+0x2e4/0x3f0 net/tipc/group.c:227
  tipc_sk_leave+0x113/0x220 net/tipc/socket.c:2863
  tipc_setsockopt+0x97d/0xd70 net/tipc/socket.c:2947
  __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
  __do_sys_setsockopt net/socket.c:1913 [inline]
  __se_sys_setsockopt net/socket.c:1910 [inline]
  __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881c59f5000
  which belongs to the cache kmalloc-192 of size 192
The buggy address is located 0 bytes inside of
  192-byte region [ffff8881c59f5000, ffff8881c59f50c0)
The buggy address belongs to the page:
page:ffffea0007167d40 count:1 mapcount:0 mapping:ffff8881da800040 index:0x0
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffffea0007160488 ffffea00071aff08 ffff8881da800040
raw: 0000000000000000 ffff8881c59f5000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881c59f4f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8881c59f4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8881c59f5000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                    ^
  ffff8881c59f5080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
  ffff8881c59f5100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


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