Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752225AbdCCOMo (ORCPT ); Fri, 3 Mar 2017 09:12:44 -0500 Received: from mail-ua0-f182.google.com ([209.85.217.182]:33071 "EHLO mail-ua0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751009AbdCCOMm (ORCPT ); Fri, 3 Mar 2017 09:12:42 -0500 MIME-Version: 1.0 In-Reply-To: References: From: Dmitry Vyukov Date: Fri, 3 Mar 2017 15:11:59 +0100 Message-ID: Subject: Re: net/dccp: use-after-free in dccp_feat_activate_values To: Cong Wang Cc: Andrey Konovalov , Gerrit Renker , "David S. Miller" , dccp@vger.kernel.org, netdev , LKML , Eric Dumazet , Kostya Serebryany , syzkaller Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9302 Lines: 193 On Mon, Feb 13, 2017 at 11:29 PM, Cong Wang wrote: > On Mon, Feb 13, 2017 at 11:19 AM, Andrey Konovalov > 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: >> >> __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: __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 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 ==================================================================