general protection fault in btrfs_scan_one_device

From: syzbot
Date: Thu Nov 15 2018 - 12:30:12 EST

Hello,

syzbot found the following crash on:

HEAD commit: 442b8cea2477 Add linux-next specific files for 20181109
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=173046a3400000
kernel config: https://syzkaller.appspot.com/x/.config?x=2f72bdb11df9fbe8
dashboard link: https://syzkaller.appspot.com/bug?extid=46048b9c7ec2fe0d4885
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+46048b9c7ec2fe0d4885@xxxxxxxxxxxxxxxxxxxxxxxxx

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 13175 Comm: syz-executor4 Not tainted 4.20.0-rc1-next-20181109+ #110
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
kobject: 'kvm' (000000001e39937e): kobject_uevent_env
RIP: 0010:device_list_add+0x436/0x1460 fs/btrfs/volumes.c:899
Code: e8 6f d3 8a fe 31 ff 4c 89 f6 e8 95 d4 8a fe 49 8d 7d 20 4d 85 f6 48 b8 00 00 00 00 00 fc ff df 48 89 fa 0f 95 c3 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e 32 0d 00 00 41 88 5d 20 4c 89 ee 48
RSP: 0018:ffff8801cbe46f30 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: ffffffff8982db01 RCX: ffffffff82f4d54b
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000014
RBP: ffff8801cbe47148 R08: ffff88017aa6e600 R09: ffffed003b5e5b67
kobject: 'kvm' (000000001e39937e): fill_kobj_path: path = '/devices/virtual/misc/kvm'
R10: ffffed003b5e5b67 R11: ffff8801daf2db3b R12: ffff8801cca11000
R13: fffffffffffffff4 R14: 0000001000000000 R15: 00000000ffffff14
FS: 00007f250ed2a700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe28d69f88 CR3: 00000001bf7b1000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
btrfs_scan_one_device+0x4bc/0x1470 fs/btrfs/volumes.c:1422
kobject: 'kvm' (000000001e39937e): kobject_uevent_env
kobject: 'ip_vti0' (000000006f23136f): kobject_add_internal: parent: 'net', set: 'devices'
kobject: 'kvm' (000000001e39937e): fill_kobj_path: path = '/devices/virtual/misc/kvm'
kobject: 'ip_vti0' (000000006f23136f): kobject_uevent_env
kobject: 'ip_vti0' (000000006f23136f): fill_kobj_path: path = '/devices/virtual/net/ip_vti0'
kobject: 'queues' (00000000975f6f6c): kobject_add_internal: parent: 'ip_vti0', set: '<NULL>'
btrfs_mount_root+0xc86/0x1d80 fs/btrfs/super.c:1568
kobject: 'queues' (00000000975f6f6c): kobject_uevent_env
legacy_get_tree+0x12f/0x260 fs/fs_context.c:714
vfs_get_tree+0x1cb/0x5c0 fs/super.c:1795
kobject: 'queues' (00000000975f6f6c): kobject_uevent_env: filter function caused the event to drop!
vfs_kern_mount.part.57+0x122/0x1a0 fs/namespace.c:3345
vfs_kern_mount+0x4a/0x70 fs/namespace.c:3324
btrfs_mount+0x4b4/0x2165 fs/btrfs/super.c:1672
kobject: 'rx-0' (00000000b0416e92): kobject_add_internal: parent: 'queues', set: 'queues'
kobject: 'rx-0' (00000000b0416e92): kobject_uevent_env
kobject: 'rx-0' (00000000b0416e92): fill_kobj_path: path = '/devices/virtual/net/ip_vti0/queues/rx-0'
kobject: 'tx-0' (00000000c8feb95b): kobject_add_internal: parent: 'queues', set: 'queues'
kobject: 'tx-0' (00000000c8feb95b): kobject_uevent_env
kobject: 'tx-0' (00000000c8feb95b): fill_kobj_path: path = '/devices/virtual/net/ip_vti0/queues/tx-0'
legacy_get_tree+0x12f/0x260 fs/fs_context.c:714
kobject: 'ip6_vti0' (000000008583c444): kobject_add_internal: parent: 'net', set: 'devices'
vfs_get_tree+0x1cb/0x5c0 fs/super.c:1795
do_new_mount fs/namespace.c:2716 [inline]
do_mount+0x82a/0x1ff0 fs/namespace.c:3042
kobject: 'ip6_vti0' (000000008583c444): kobject_uevent_env
kobject: 'ip6_vti0' (000000008583c444): fill_kobj_path: path = '/devices/virtual/net/ip6_vti0'
ksys_mount+0x12d/0x140 fs/namespace.c:3258
__do_sys_mount fs/namespace.c:3272 [inline]
__se_sys_mount fs/namespace.c:3269 [inline]
__x64_sys_mount+0xbe/0x150 fs/namespace.c:3269
kobject: 'queues' (00000000ed64f9a7): kobject_add_internal: parent: 'ip6_vti0', set: '<NULL>'
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
kobject: 'queues' (00000000ed64f9a7): kobject_uevent_env
kobject: 'queues' (00000000ed64f9a7): kobject_uevent_env: filter function caused the event to drop!
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459fda
Code: b8 a6 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 7d 89 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 0f 83 5a 89 fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007f250ed29a88 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
kobject: 'rx-0' (00000000c0c5ba02): kobject_add_internal: parent: 'queues', set: 'queues'
RAX: ffffffffffffffda RBX: 00007f250ed29b30 RCX: 0000000000459fda
RDX: 00007f250ed29ad0 RSI: 0000000020000100 RDI: 00007f250ed29af0
RBP: 0000000020000100 R08: 00007f250ed29b30 R09: 00007f250ed29ad0
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000004
R13: 0000000000000000 R14: 00000000004d83e8 R15: 0000000000000003
Modules linked in:
kobject: 'loop5' (000000004b229921): kobject_uevent_env
kobject: 'loop5' (000000004b229921): fill_kobj_path: path = '/devices/virtual/block/loop5'
---[ end trace 6d0d7474702a14d9 ]---
kobject: 'loop4' (0000000090ac9b5a): kobject_uevent_env
RIP: 0010:device_list_add+0x436/0x1460 fs/btrfs/volumes.c:899
kobject: 'loop4' (0000000090ac9b5a): fill_kobj_path: path = '/devices/virtual/block/loop4'
Code: e8 6f d3 8a fe 31 ff 4c 89 f6 e8 95 d4 8a fe 49 8d 7d 20 4d 85 f6 48 b8 00 00 00 00 00 fc ff df 48 89 fa 0f 95 c3 48 c1 ea 03 <0f> b6 04 02 84 c0 74 06 0f 8e 32 0d 00 00 41 88 5d 20 4c 89 ee 48
kobject: 'loop1' (0000000002c6f40b): kobject_uevent_env
kobject: 'kvm' (000000001e39937e): kobject_uevent_env
kobject: 'loop1' (0000000002c6f40b): fill_kobj_path: path = '/devices/virtual/block/loop1'
RSP: 0018:ffff8801cbe46f30 EFLAGS: 00010203
kobject: 'rx-0' (00000000c0c5ba02): kobject_uevent_env
RAX: dffffc0000000000 RBX: ffffffff8982db01 RCX: ffffffff82f4d54b
kobject: 'kvm' (000000001e39937e): fill_kobj_path: path = '/devices/virtual/misc/kvm'
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000014
kobject: 'rx-0' (00000000c0c5ba02): fill_kobj_path: path = '/devices/virtual/net/ip6_vti0/queues/rx-0'
RBP: ffff8801cbe47148 R08: ffff88017aa6e600 R09: ffffed003b5e5b67
kobject: 'loop5' (000000004b229921): kobject_uevent_env
kobject: 'loop5' (000000004b229921): fill_kobj_path: path = '/devices/virtual/block/loop5'
R10: ffffed003b5e5b67 R11: ffff8801daf2db3b R12: ffff8801cca11000
kobject: 'tx-0' (00000000dad0d615): kobject_add_internal: parent: 'queues', set: 'queues'
R13: fffffffffffffff4 R14: 0000001000000000 R15: 00000000ffffff14
kobject: 'tx-0' (00000000dad0d615): kobject_uevent_env
FS: 00007f250ed2a700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kobject: 'tx-0' (00000000dad0d615): fill_kobj_path: path = '/devices/virtual/net/ip6_vti0/queues/tx-0'
kobject: 'loop5' (000000004b229921): kobject_uevent_env
CR2: 0000000000728000 CR3: 00000001bf7b1000 CR4: 00000000001406f0
kobject: 'loop5' (000000004b229921): fill_kobj_path: path = '/devices/virtual/block/loop5'
IPVS: ftp: loaded support on port[0] = 21
kobject: 'loop1' (0000000002c6f40b): kobject_uevent_env
kobject: 'loop1' (0000000002c6f40b): fill_kobj_path: path = '/devices/virtual/block/loop1'
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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