Subject: kernel BUG at net/core/net-sysfs.c:LINE!

From: syzbot <[email-masked]>
Date: Sat, 23 Mar 2019 00:32:06 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    e382d91f Add linux-next specific files for 20190322
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1737671b200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3d850e8b394c7a19
dashboard link: https://syzkaller.appspot.com/bug?extid=6024817a931b2830bc93
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1795613b200000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10f5a437200000

The bug was bisected to:

commit 6b70fc94afd165342876e53fc4b2f7d085009945
Author: Wang Hai <[email-masked]>
Date:   Wed Mar 20 18:25:05 2019 +0000

     net-sysfs: Fix memory leak in netdev_register_kobject

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1522556d200000
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1722556d200000
console output: https://syzkaller.appspot.com/x/log.txt?x=1322556d200000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]
Fixes: 6b70fc94afd1 ("net-sysfs: Fix memory leak in  
netdev_register_kobject")

RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000441399
RDX: 0000000020000080 RSI: 00000000000089f1 RDI: 0000000000000006
RBP: 00007ffcd20666d0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000007 R14: 0000000000000000 R15: 0000000000000000
------------[ cut here ]------------
kernel BUG at net/core/net-sysfs.c:1631!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 8035 Comm: syz-executor344 Not tainted 5.1.0-rc1-next-20190322  
#9
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:netdev_release net/core/net-sysfs.c:1631 [inline]
RIP: 0010:netdev_release+0x92/0xb0 net/core/net-sysfs.c:1627
Code: 48 c1 ea 03 80 3c 02 00 75 29 48 8b bb 80 fa ff ff e8 12 77 20 fc 4c  
89 ef e8 7a cc f5 ff 5b 41 5c 41 5d 5d c3 e8 9e 9b e8 fb <0f> 0b e8 27 b1  
20 fc eb 9c e8 80 b1 20 fc eb d0 0f 1f 40 00 66 2e
RSP: 0018:ffff88808d6af718 EFLAGS: 00010293
RAX: ffff8880a87902c0 RBX: ffff88808e3612a0 RCX: ffffffff8587fc89
RDX: 0000000000000000 RSI: ffffffff8587fcd2 RDI: 0000000000000001
RBP: ffff88808d6af730 R08: ffff8880a87902c0 R09: ffff8880a8790b60
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88808e360d00 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000001752880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000098da2000 CR4: 00000000001406e0
Call Trace:
  device_release+0x7d/0x210 drivers/base/core.c:1064
  kobject_cleanup lib/kobject.c:662 [inline]
  kobject_release lib/kobject.c:691 [inline]
  kref_put include/linux/kref.h:67 [inline]
  kobject_put.cold+0x28f/0x2ec lib/kobject.c:708
  put_device+0x20/0x30 drivers/base/core.c:2205
  netdev_register_kobject+0x1a1/0x3c0 net/core/net-sysfs.c:1763
  register_netdevice+0x878/0xff0 net/core/dev.c:8709
  ip6_tnl_create2+0x1c2/0x350 net/ipv6/ip6_tunnel.c:269
  ip6_tnl_create net/ipv6/ip6_tunnel.c:320 [inline]
  ip6_tnl_locate+0x63f/0x8d0 net/ipv6/ip6_tunnel.c:368
  ip6_tnl_ioctl+0x490/0xab0 net/ipv6/ip6_tunnel.c:1634
  dev_ifsioc+0x257/0x990 net/core/dev_ioctl.c:322
  dev_ioctl+0x286/0xc90 net/core/dev_ioctl.c:513
  sock_ioctl+0x48b/0x610 net/socket.c:1102
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:509 [inline]
  do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696
  ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
  __do_sys_ioctl fs/ioctl.c:720 [inline]
  __se_sys_ioctl fs/ioctl.c:718 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
  do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441399
Code: e8 5c ae 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 bb 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffcd20666b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000441399
RDX: 0000000020000080 RSI: 00000000000089f1 RDI: 0000000000000006
RBP: 00007ffcd20666d0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000007 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 0dbf190846958075 ]---
RIP: 0010:netdev_release net/core/net-sysfs.c:1631 [inline]
RIP: 0010:netdev_release+0x92/0xb0 net/core/net-sysfs.c:1627
Code: 48 c1 ea 03 80 3c 02 00 75 29 48 8b bb 80 fa ff ff e8 12 77 20 fc 4c  
89 ef e8 7a cc f5 ff 5b 41 5c 41 5d 5d c3 e8 9e 9b e8 fb <0f> 0b e8 27 b1  
20 fc eb 9c e8 80 b1 20 fc eb d0 0f 1f 40 00 66 2e
RSP: 0018:ffff88808d6af718 EFLAGS: 00010293
RAX: ffff8880a87902c0 RBX: ffff88808e3612a0 RCX: ffffffff8587fc89
RDX: 0000000000000000 RSI: ffffffff8587fcd2 RDI: 0000000000000001
RBP: ffff88808d6af730 R08: ffff8880a87902c0 R09: ffff8880a8790b60
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88808e360d00 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000001752880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000098da2000 CR4: 00000000001406e0

---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at [email-masked].

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches