Re: net/dccp: use-after-free in dccp_feat_activate_values

From: Dmitry Vyukov
Date: Fri Mar 03 2017 - 09:13:58 EST

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In reply to: Dmitry Vyukov: "Re: net/dccp: use-after-free in dccp_feat_activate_values"
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On Fri, Mar 3, 2017 at 3:11 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> On Mon, Feb 13, 2017 at 11:29 PM, Cong Wang <xiyou.wangcong@xxxxxxxxx> wrote:
>> On Mon, Feb 13, 2017 at 11:19 AM, Andrey Konovalov
>> <andreyknvl@xxxxxxxxxx> wrote:
>>> Hi,
>>>
>>> I've got the following error report while fuzzing the kernel with syzkaller.
>>>
>>> On commit 926af6273fc683cd98cd0ce7bf0d04a02eed6742.
>>>
>>> A reproducer and .config are attached.
>>> Note, that it takes quite some time to trigger the bug (up to 10 minutes).
>>>
>>> BUG: KASAN: use-after-free in dccp_feat_activate_values+0x967/0xab0
>>> net/dccp/feat.c:1541 at addr ffff88003713be68
>>> Read of size 8 by task syz-executor2/8457
>>> CPU: 2 PID: 8457 Comm: syz-executor2 Not tainted 4.10.0-rc7+ #127
>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>> Call Trace:
>>> <IRQ>
>>> __dump_stack lib/dump_stack.c:15 [inline]
>>> dump_stack+0x292/0x398 lib/dump_stack.c:51
>>> kasan_object_err+0x1c/0x70 mm/kasan/report.c:162
>>> print_address_description mm/kasan/report.c:200 [inline]
>>> kasan_report_error mm/kasan/report.c:289 [inline]
>>> kasan_report.part.1+0x20e/0x4e0 mm/kasan/report.c:311
>>> kasan_report mm/kasan/report.c:332 [inline]
>>> __asan_report_load8_noabort+0x29/0x30 mm/kasan/report.c:332
>>> dccp_feat_activate_values+0x967/0xab0 net/dccp/feat.c:1541
>>> dccp_create_openreq_child+0x464/0x610 net/dccp/minisocks.c:121
>>> dccp_v6_request_recv_sock+0x1f6/0x1960 net/dccp/ipv6.c:457
>>> dccp_check_req+0x335/0x5a0 net/dccp/minisocks.c:186
>>> dccp_v6_rcv+0x69e/0x1d00 net/dccp/ipv6.c:711
>>> ip6_input_finish+0x46d/0x17a0 net/ipv6/ip6_input.c:279
>>> NF_HOOK include/linux/netfilter.h:257 [inline]
>>> ip6_input+0xdb/0x590 net/ipv6/ip6_input.c:322
>>> dst_input include/net/dst.h:507 [inline]
>>> ip6_rcv_finish+0x289/0x890 net/ipv6/ip6_input.c:69
>>> NF_HOOK include/linux/netfilter.h:257 [inline]
>>> ipv6_rcv+0x12ec/0x23d0 net/ipv6/ip6_input.c:203
>>> __netif_receive_skb_core+0x1ae5/0x3400 net/core/dev.c:4190
>>> __netif_receive_skb+0x2a/0x170 net/core/dev.c:4228
>>> process_backlog+0xe5/0x6c0 net/core/dev.c:4839
>>> napi_poll net/core/dev.c:5202 [inline]
>>> net_rx_action+0xe70/0x1900 net/core/dev.c:5267
>>> __do_softirq+0x2fb/0xb7d kernel/softirq.c:284
>>> do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:902
>>
>>
>> Seems there is a race condition between iterating dccp_feat_entry
>> and freeing it, bh_lock_sock() seems not held in this path.
>
>
>
> Cong, where exactly do we need to add bh_lock_sock()?
>
> I am still seeing this on 4977ab6e92e267afe9d8f78438c3db330ca8434c
>
> ==================================================================
> BUG: KASAN: use-after-free in dccp_feat_activate_values+0x94c/0xa90
> net/dccp/feat.c:1541 at addr ffff880059f18998
> Read of size 8 by task syz-executor/3952
> CPU: 2 PID: 3952 Comm: syz-executor Not tainted 4.10.0+ #269
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> Call Trace:
> <IRQ>
> __dump_stack lib/dump_stack.c:15 [inline]
> dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
> kasan_object_err+0x1c/0x70 mm/kasan/report.c:166
> print_address_description mm/kasan/report.c:204 [inline]
> kasan_report_error mm/kasan/report.c:288 [inline]
> kasan_report.part.2+0x198/0x440 mm/kasan/report.c:310
> kasan_report mm/kasan/report.c:331 [inline]
> __asan_report_load8_noabort+0x29/0x30 mm/kasan/report.c:331
> dccp_feat_activate_values+0x94c/0xa90 net/dccp/feat.c:1541
> dccp_create_openreq_child+0x464/0x610 net/dccp/minisocks.c:121
> dccp_v6_request_recv_sock+0x1f1/0x17e0 net/dccp/ipv6.c:457
> dccp_check_req+0x335/0x5a0 net/dccp/minisocks.c:186
> dccp_v6_rcv+0x653/0x1d10 net/dccp/ipv6.c:711
> ip6_input_finish+0x45b/0x1700 net/ipv6/ip6_input.c:279
> NF_HOOK include/linux/netfilter.h:257 [inline]
> ip6_input+0xdb/0x580 net/ipv6/ip6_input.c:322
> dst_input include/net/dst.h:492 [inline]
> ip6_rcv_finish+0x194/0x720 net/ipv6/ip6_input.c:69
> NF_HOOK include/linux/netfilter.h:257 [inline]
> ipv6_rcv+0x12df/0x2380 net/ipv6/ip6_input.c:203
> __netif_receive_skb_core+0x1ac8/0x33f0 net/core/dev.c:4179
> __netif_receive_skb+0x2a/0x170 net/core/dev.c:4217
> process_backlog+0x11e/0x730 net/core/dev.c:4837
> napi_poll net/core/dev.c:5171 [inline]
> net_rx_action+0xf0a/0x1980 net/core/dev.c:5236
> __do_softirq+0x31f/0xbe7 kernel/softirq.c:284
> do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:902
> </IRQ>
> do_softirq.part.21+0x2c0/0x300 kernel/softirq.c:328
> do_softirq kernel/softirq.c:176 [inline]
> __local_bh_enable_ip+0x24c/0x290 kernel/softirq.c:181
> local_bh_enable include/linux/bottom_half.h:31 [inline]
> rcu_read_unlock_bh include/linux/rcupdate.h:971 [inline]
> ip6_finish_output2+0xb85/0x2380 net/ipv6/ip6_output.c:124
> ip6_finish_output+0x2f9/0x950 net/ipv6/ip6_output.c:149
> NF_HOOK_COND include/linux/netfilter.h:246 [inline]
> ip6_output+0x1cb/0x8c0 net/ipv6/ip6_output.c:163
> ip6_xmit+0xc36/0x1e80 include/net/dst.h:486
> inet6_csk_xmit+0x320/0x5d0 net/ipv6/inet6_connection_sock.c:139
> dccp_transmit_skb+0xac5/0x10e0 net/dccp/output.c:141
> dccp_xmit_packet+0x20f/0x750 net/dccp/output.c:280
> dccp_write_xmit+0x168/0x1d0 net/dccp/output.c:362
> dccp_sendmsg+0x793/0xb00 net/dccp/proto.c:796
> inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:761
> sock_sendmsg_nosec net/socket.c:633 [inline]
> sock_sendmsg+0xca/0x110 net/socket.c:643
> SYSC_sendto+0x660/0x810 net/socket.c:1685
> SyS_sendto+0x40/0x50 net/socket.c:1653
> entry_SYSCALL_64_fastpath+0x1f/0xc2
> RIP: 0033:0x4458d9
> RSP: 002b:00007f59f536bb58 EFLAGS: 00000282 ORIG_RAX: 000000000000002c
> RAX: ffffffffffffffda RBX: 000000000000001a RCX: 00000000004458d9
> RDX: 0000000000000037 RSI: 0000000020e62000 RDI: 000000000000001a
> RBP: 00000000006e1b90 R08: 0000000020e62fe0 R09: 0000000000000020
> R10: 0000000000008000 R11: 0000000000000282 R12: 0000000000708150
> R13: 0000000020d0aff8 R14: 0000000000000004 R15: 0000000000000000
> Object at ffff880059f18980, in cache kmalloc-64 size: 64
> Allocated:
> PID = 3932
> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
> save_stack+0x43/0xd0 mm/kasan/kasan.c:502
> set_track mm/kasan/kasan.c:514 [inline]
> kasan_kmalloc+0xaa/0xd0 mm/kasan/kasan.c:605
> kmem_cache_alloc_trace+0x10b/0x6e0 mm/slab.c:3637
> kmalloc include/linux/slab.h:490 [inline]
> dccp_feat_entry_new+0x20b/0x400 net/dccp/feat.c:467
> dccp_feat_push_change+0x38/0x220 net/dccp/feat.c:487
> __feat_register_sp+0x223/0x2f0 net/dccp/feat.c:741
> dccp_feat_propagate_ccid+0x22b/0x2b0 net/dccp/feat.c:949
> dccp_feat_server_ccid_dependencies+0x1b3/0x250 net/dccp/feat.c:1012
> dccp_make_response+0x1f1/0xc50 net/dccp/output.c:423
> dccp_v6_send_response+0x4ec/0xc20 net/dccp/ipv6.c:217
> dccp_v6_conn_request+0xab2/0x1100 net/dccp/ipv6.c:377
> dccp_rcv_state_process+0x50c/0x1650 net/dccp/input.c:606
> dccp_v6_do_rcv+0x20d/0x350 net/dccp/ipv6.c:632
> sk_backlog_rcv include/net/sock.h:896 [inline]
> __sk_receive_skb+0x350/0xca0 net/core/sock.c:479
> dccp_v6_rcv+0xb17/0x1d10 net/dccp/ipv6.c:742
> ip6_input_finish+0x45b/0x1700 net/ipv6/ip6_input.c:279
> NF_HOOK include/linux/netfilter.h:257 [inline]
> ip6_input+0xdb/0x580 net/ipv6/ip6_input.c:322
> dst_input include/net/dst.h:492 [inline]
> ip6_rcv_finish+0x194/0x720 net/ipv6/ip6_input.c:69
> NF_HOOK include/linux/netfilter.h:257 [inline]
> ipv6_rcv+0x12df/0x2380 net/ipv6/ip6_input.c:203
> __netif_receive_skb_core+0x1ac8/0x33f0 net/core/dev.c:4179
> __netif_receive_skb+0x2a/0x170 net/core/dev.c:4217
> process_backlog+0x11e/0x730 net/core/dev.c:4837
> napi_poll net/core/dev.c:5171 [inline]
> net_rx_action+0xf0a/0x1980 net/core/dev.c:5236
> __do_softirq+0x31f/0xbe7 kernel/softirq.c:284
> Freed:
> PID = 24
> save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
> save_stack+0x43/0xd0 mm/kasan/kasan.c:502
> set_track mm/kasan/kasan.c:514 [inline]
> kasan_slab_free+0x6f/0xb0 mm/kasan/kasan.c:578
> __cache_free mm/slab.c:3513 [inline]
> kfree+0xd3/0x250 mm/slab.c:3830
> dccp_feat_entry_destructor.part.4+0x48/0x60 net/dccp/feat.c:418
> dccp_feat_entry_destructor net/dccp/feat.c:416 [inline]
> dccp_feat_list_pop net/dccp/feat.c:541 [inline]
> dccp_feat_activate_values+0x57f/0xa90 net/dccp/feat.c:1543
> dccp_create_openreq_child+0x464/0x610 net/dccp/minisocks.c:121
> dccp_v6_request_recv_sock+0x1f1/0x17e0 net/dccp/ipv6.c:457
> dccp_check_req+0x335/0x5a0 net/dccp/minisocks.c:186
> dccp_v6_rcv+0x653/0x1d10 net/dccp/ipv6.c:711
> ip6_input_finish+0x45b/0x1700 net/ipv6/ip6_input.c:279
> NF_HOOK include/linux/netfilter.h:257 [inline]
> ip6_input+0xdb/0x580 net/ipv6/ip6_input.c:322
> dst_input include/net/dst.h:492 [inline]
> ip6_rcv_finish+0x194/0x720 net/ipv6/ip6_input.c:69
> NF_HOOK include/linux/netfilter.h:257 [inline]
> ipv6_rcv+0x12df/0x2380 net/ipv6/ip6_input.c:203
> __netif_receive_skb_core+0x1ac8/0x33f0 net/core/dev.c:4179
> __netif_receive_skb+0x2a/0x170 net/core/dev.c:4217
> process_backlog+0x11e/0x730 net/core/dev.c:4837
> napi_poll net/core/dev.c:5171 [inline]
> net_rx_action+0xf0a/0x1980 net/core/dev.c:5236
> __do_softirq+0x31f/0xbe7 kernel/softirq.c:284
> Memory state around the buggy address:
> ffff880059f18880: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
> ffff880059f18900: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>>ffff880059f18980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ^
> ffff880059f18a00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
> ffff880059f18a80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================

Hit this while trying to reproduce another WARNING in networking
stack, so now I suspect that it may be an induced WARNING and not sure
if it worth pursuing spending more time on it...

WARNING: CPU: 1 PID: 29691 at net/core/stream.c:198
sk_stream_kill_queues+0x401/0x570 net/core/stream.c:198
Call Trace:
__dump_stack lib/dump_stack.c:15 [inline]
dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
panic+0x1fb/0x412 kernel/panic.c:179
__warn+0x1c4/0x1e0 kernel/panic.c:539
warn_slowpath_null+0x2c/0x40 kernel/panic.c:582
sk_stream_kill_queues+0x401/0x570 net/core/stream.c:198
inet_csk_destroy_sock+0x175/0x450 net/ipv4/inet_connection_sock.c:708
dccp_close+0x951/0xc60 net/dccp/proto.c:1067
inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425
inet6_release+0x50/0x70 net/ipv6/af_inet6.c:431
sock_release+0x8d/0x1e0 net/socket.c:599
sock_close+0x16/0x20 net/socket.c:1063
__fput+0x332/0x7f0 fs/file_table.c:208
____fput+0x15/0x20 fs/file_table.c:244
task_work_run+0x18a/0x260 kernel/task_work.c:116
exit_task_work include/linux/task_work.h:21 [inline]
do_exit+0x18ef/0x28b0 kernel/exit.c:841
do_group_exit+0x149/0x420 kernel/exit.c:945
get_signal+0x7e0/0x1820 kernel/signal.c:2313
do_signal+0xd2/0x2190 arch/x86/kernel/signal.c:807
exit_to_usermode_loop+0x200/0x2a0 arch/x86/entry/common.c:156
prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline]
syscall_return_slowpath+0x4d3/0x570 arch/x86/entry/common.c:259
entry_SYSCALL_64_fastpath+0xc0/0xc2

Next message: Richard Genoud: "[PATCH 2/4] tty/serial: atmel: remove uneeded IS_ERR_OR_NULL calls"
Previous message: Boris Brezillon: "Re: [PATCH 2/3] mtd: Add support for reading MTD devices via the nvmem API"
In reply to: Dmitry Vyukov: "Re: net/dccp: use-after-free in dccp_feat_activate_values"
Next in thread: Eric Dumazet: "Re: net/dccp: use-after-free in dccp_feat_activate_values"
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