KASAN: use-after-free Read in vhost_work_queue

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 33e17876ea4e Merge branch 'akpm' (patches from Andrew)
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12d8a20a400000
kernel config: https://syzkaller.appspot.com/x/.config?x=40e5d6b26b73cd5b
dashboard link: https://syzkaller.appspot.com/bug?extid=d5a0a170c5069658b141
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
userspace arch: i386

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+d5a0a1...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in vhost_work_queue+0xc3/0xe0
drivers/vhost/vhost.c:258
Read of size 8 at addr ffff880193862068 by task syz-executor7/22100

CPU: 0 PID: 22100 Comm: syz-executor7 Not tainted 4.18.0+ #108
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+0x1c9/0x2b4 lib/dump_stack.c:113
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
vhost_work_queue+0xc3/0xe0 drivers/vhost/vhost.c:258
vhost_transport_send_pkt+0x28a/0x380 drivers/vhost/vsock.c:227
virtio_transport_send_pkt_info+0x31d/0x460
net/vmw_vsock/virtio_transport_common.c:190
virtio_transport_shutdown+0x1b1/0x270
net/vmw_vsock/virtio_transport_common.c:604
vsock_send_shutdown net/vmw_vsock/af_vsock.c:451 [inline]
vsock_shutdown+0x229/0x290 net/vmw_vsock/af_vsock.c:849
__sys_shutdown+0x15c/0x2c0 net/socket.c:1964
__do_sys_shutdown net/socket.c:1972 [inline]
__se_sys_shutdown net/socket.c:1970 [inline]
__ia32_sys_shutdown+0x54/0x80 net/socket.c:1970
do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline]
do_fast_syscall_32+0x34d/0xfb2 arch/x86/entry/common.c:397
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fa4ca9
Code: 55 08 8b 88 64 cd ff ff 8b 98 68 cd ff ff 89 c8 85 d2 74 02 89 0a 5b
5d c3 8b 04 24 c3 8b 1c 24 c3 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90
90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5f7f0cc EFLAGS: 00000296 ORIG_RAX: 0000000000000175
RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 22094:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node+0x47/0x70 mm/slab.c:3689
kmalloc_node include/linux/slab.h:555 [inline]
kvmalloc_node+0xb9/0xf0 mm/util.c:423
kvmalloc include/linux/mm.h:577 [inline]
vhost_vsock_dev_open+0xa2/0x5a0 drivers/vhost/vsock.c:511
misc_open+0x3ca/0x560 drivers/char/misc.c:141
chrdev_open+0x25a/0x770 fs/char_dev.c:417
do_dentry_open+0x49c/0x1140 fs/open.c:771
vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3418 [inline]
path_openat+0x12fb/0x5300 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x584/0x720 fs/open.c:1063
__do_compat_sys_openat fs/open.c:1109 [inline]
__se_compat_sys_openat fs/open.c:1107 [inline]
__ia32_compat_sys_openat+0x98/0xf0 fs/open.c:1107
do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline]
do_fast_syscall_32+0x34d/0xfb2 arch/x86/entry/common.c:397
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Freed by task 22093:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xd9/0x210 mm/slab.c:3813
kvfree+0x61/0x70 mm/util.c:449
vhost_vsock_free drivers/vhost/vsock.c:499 [inline]
vhost_vsock_dev_release+0x4fd/0x750 drivers/vhost/vsock.c:604
__fput+0x36e/0x8c0 fs/file_table.c:278
____fput+0x15/0x20 fs/file_table.c:309
task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_32_irqs_on arch/x86/entry/common.c:341 [inline]
do_fast_syscall_32+0xcd5/0xfb2 arch/x86/entry/common.c:397
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

The buggy address belongs to the object at ffff880193861fc0
which belongs to the cache kmalloc-65536 of size 65536
The buggy address is located 168 bytes inside of
65536-byte region [ffff880193861fc0, ffff880193871fc0)
The buggy address belongs to the page:
page:ffffea00064e1800 count:1 mapcount:0 mapping:ffff8801dac02500 index:0x0
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffffea00064c7008 ffffea00064e5008 ffff8801dac02500
raw: 0000000000000000 ffff880193861fc0 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff880193861f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff880193861f80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> ffff880193862000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff880193862080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff880193862100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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 syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
syzbot.

[Michael S. Tsirkin]

Seems like a duplicate of the bug Stefan's working on now.

[Stefan Hajnoczi]

I am currently away on leave and not working on fixes. Please contact
Cathy about vsock syzkaller bugs while I'm away.

Stefan

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 46c163a036b4 Add linux-next specific files for 20180921
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10c6792a400000
kernel config: https://syzkaller.appspot.com/x/.config?x=20ea07a946ad19d7

dashboard link: https://syzkaller.appspot.com/bug?extid=d5a0a170c5069658b141
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=130cec76400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+d5a0a1...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0

==================================================================
BUG: KASAN: use-after-free in vhost_work_queue+0xc3/0xe0
drivers/vhost/vhost.c:258

Read of size 8 at addr ffff8801b05432a8 by task syz-executor0/9644

CPU: 1 PID: 9644 Comm: syz-executor0 Not tainted 4.19.0-rc4-next-20180921+
#77

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+0x1d3/0x2c4 lib/dump_stack.c:113
print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412

__asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
vhost_work_queue+0xc3/0xe0 drivers/vhost/vhost.c:258
vhost_transport_send_pkt+0x28a/0x380 drivers/vhost/vsock.c:227
virtio_transport_send_pkt_info+0x31d/0x460
net/vmw_vsock/virtio_transport_common.c:190

virtio_transport_connect+0x17c/0x220
net/vmw_vsock/virtio_transport_common.c:588
vsock_stream_connect+0x4ed/0xe40 net/vmw_vsock/af_vsock.c:1200
__sys_connect+0x37d/0x4c0 net/socket.c:1665
__do_sys_connect net/socket.c:1676 [inline]
__se_sys_connect net/socket.c:1673 [inline]
__x64_sys_connect+0x73/0xb0 net/socket.c:1673
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457679
Code: 1d b4 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 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f746bbf5c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f746bbf66d4 RCX: 0000000000457679
RDX: 0000000000000010 RSI: 0000000020000200 RDI: 0000000000000009
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004cc658 R14: 00000000004bdcb3 R15: 0000000000000000

Allocated by task 9654:

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

__do_kmalloc_node mm/slab.c:3682 [inline]
__kmalloc_node+0x47/0x70 mm/slab.c:3689

kmalloc_node include/linux/slab.h:589 [inline]

kvmalloc_node+0xb9/0xf0 mm/util.c:423
kvmalloc include/linux/mm.h:577 [inline]
vhost_vsock_dev_open+0xa2/0x5a0 drivers/vhost/vsock.c:511
misc_open+0x3ca/0x560 drivers/char/misc.c:141

chrdev_open+0x25a/0x710 fs/char_dev.c:417
do_dentry_open+0x499/0x1250 fs/open.c:771

vfs_open+0xa0/0xd0 fs/open.c:880
do_last fs/namei.c:3418 [inline]

path_openat+0x12bc/0x5160 fs/namei.c:3534
do_filp_open+0x255/0x380 fs/namei.c:3564
do_sys_open+0x568/0x700 fs/open.c:1063
__do_sys_openat fs/open.c:1090 [inline]
__se_sys_openat fs/open.c:1084 [inline]
__x64_sys_openat+0x9d/0x100 fs/open.c:1084
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9643:

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:3813
kvfree+0x61/0x70 mm/util.c:452
vhost_vsock_free drivers/vhost/vsock.c:499 [inline]
vhost_vsock_dev_release+0x4f4/0x720 drivers/vhost/vsock.c:604
__fput+0x3bc/0xa70 fs/file_table.c:279
____fput+0x15/0x20 fs/file_table.c:312

task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]

do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801b0543200
which belongs to the cache kmalloc-64k of size 65536

The buggy address is located 168 bytes inside of

65536-byte region [ffff8801b0543200, ffff8801b0553200)

The buggy address belongs to the page:

page:ffffea0006c15000 count:1 mapcount:0 mapping:ffff8801da802500 index:0x0
compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea0006c14808 ffffea0006c15808 ffff8801da802500
raw: 0000000000000000 ffff8801b0543200 0000000100000001 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff8801b0543180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8801b0543200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801b0543280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8801b0543300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801b0543380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================