kernel.git/net/dccp/minisocks.c, branch linux-5.18.y

tcp: allocate tcp_death_row outside of struct netns_ipv4

2022-01-27T03:00:31Z

I forgot tcp had per netns tracking of timewait sockets, and their sysctl to change the limit. After 0dad4087a86a ("tcp/dccp: get rid of inet_twsk_purge()"), whole struct net can be freed before last tw socket is freed. We need to allocate a separate struct inet_timewait_death_row object per netns. tw_count becomes a refcount and gains associated debugging infrastructure. BUG: KASAN: use-after-free in inet_twsk_kill+0x358/0x3c0 net/ipv4/inet_timewait_sock.c:46 Read of size 8 at addr ffff88807d5f9f40 by task kworker/1:7/3690 CPU: 1 PID: 3690 Comm: kworker/1:7 Not tainted 5.16.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events pwq_unbound_release_workfn Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.c:255 __kasan_report mm/kasan/report.c:442 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 inet_twsk_kill+0x358/0x3c0 net/ipv4/inet_timewait_sock.c:46 call_timer_fn+0x1a5/0x6b0 kernel/time/timer.c:1421 expire_timers kernel/time/timer.c:1466 [inline] __run_timers.part.0+0x67c/0xa30 kernel/time/timer.c:1734 __run_timers kernel/time/timer.c:1715 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1747 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558 invoke_softirq kernel/softirq.c:432 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:637 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:lockdep_unregister_key+0x1c9/0x250 kernel/locking/lockdep.c:6328 Code: 00 00 00 48 89 ee e8 46 fd ff ff 4c 89 f7 e8 5e c9 ff ff e8 09 cc ff ff 9c 58 f6 c4 02 75 26 41 f7 c4 00 02 00 00 74 01 fb 5b <5d> 41 5c 41 5d 41 5e 41 5f e9 19 4a 08 00 0f 0b 5b 5d 41 5c 41 5d RSP: 0018:ffffc90004077cb8 EFLAGS: 00000206 RAX: 0000000000000046 RBX: ffff88807b61b498 RCX: 0000000000000001 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff888077027128 R08: 0000000000000001 R09: ffffffff8f1ea4fc R10: fffffbfff1ff93ee R11: 000000000000af1e R12: 0000000000000246 R13: 0000000000000000 R14: ffffffff8ffc89b8 R15: ffffffff90157fb0 wq_unregister_lockdep kernel/workqueue.c:3508 [inline] pwq_unbound_release_workfn+0x254/0x340 kernel/workqueue.c:3746 process_one_work+0x9ac/0x1650 kernel/workqueue.c:2307 worker_thread+0x657/0x1110 kernel/workqueue.c:2454 kthread+0x2e9/0x3a0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 Allocated by task 3635: kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:437 [inline] __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:470 kasan_slab_alloc include/linux/kasan.h:260 [inline] slab_post_alloc_hook mm/slab.h:732 [inline] slab_alloc_node mm/slub.c:3230 [inline] slab_alloc mm/slub.c:3238 [inline] kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243 kmem_cache_zalloc include/linux/slab.h:705 [inline] net_alloc net/core/net_namespace.c:407 [inline] copy_net_ns+0x125/0x760 net/core/net_namespace.c:462 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226 ksys_unshare+0x445/0x920 kernel/fork.c:3048 __do_sys_unshare kernel/fork.c:3119 [inline] __se_sys_unshare kernel/fork.c:3117 [inline] __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3117 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff88807d5f9a80 which belongs to the cache net_namespace of size 6528 The buggy address is located 1216 bytes inside of 6528-byte region [ffff88807d5f9a80, ffff88807d5fb400) The buggy address belongs to the page: page:ffffea0001f57e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88807d5f9a80 pfn:0x7d5f8 head:ffffea0001f57e00 order:3 compound_mapcount:0 compound_pincount:0 memcg:ffff888070023001 flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000010200 ffff888010dd4f48 ffffea0001404e08 ffff8880118fd000 raw: ffff88807d5f9a80 0000000000040002 00000001ffffffff ffff888070023001 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3634, ts 119694798460, free_ts 119693556950 prep_new_page mm/page_alloc.c:2434 [inline] get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271 alloc_slab_page mm/slub.c:1799 [inline] allocate_slab mm/slub.c:1944 [inline] new_slab+0x28a/0x3b0 mm/slub.c:2004 ___slab_alloc+0x87c/0xe90 mm/slub.c:3018 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105 slab_alloc_node mm/slub.c:3196 [inline] slab_alloc mm/slub.c:3238 [inline] kmem_cache_alloc+0x35c/0x3a0 mm/slub.c:3243 kmem_cache_zalloc include/linux/slab.h:705 [inline] net_alloc net/core/net_namespace.c:407 [inline] copy_net_ns+0x125/0x760 net/core/net_namespace.c:462 create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110 unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:226 ksys_unshare+0x445/0x920 kernel/fork.c:3048 __do_sys_unshare kernel/fork.c:3119 [inline] __se_sys_unshare kernel/fork.c:3117 [inline] __x64_sys_unshare+0x2d/0x40 kernel/fork.c:3117 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1352 [inline] free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404 free_unref_page_prepare mm/page_alloc.c:3325 [inline] free_unref_page+0x19/0x690 mm/page_alloc.c:3404 skb_free_head net/core/skbuff.c:655 [inline] skb_release_data+0x65d/0x790 net/core/skbuff.c:677 skb_release_all net/core/skbuff.c:742 [inline] __kfree_skb net/core/skbuff.c:756 [inline] consume_skb net/core/skbuff.c:914 [inline] consume_skb+0xc2/0x160 net/core/skbuff.c:908 skb_free_datagram+0x1b/0x1f0 net/core/datagram.c:325 netlink_recvmsg+0x636/0xea0 net/netlink/af_netlink.c:1998 sock_recvmsg_nosec net/socket.c:948 [inline] sock_recvmsg net/socket.c:966 [inline] sock_recvmsg net/socket.c:962 [inline] ____sys_recvmsg+0x2c4/0x600 net/socket.c:2632 ___sys_recvmsg+0x127/0x200 net/socket.c:2674 __sys_recvmsg+0xe2/0x1a0 net/socket.c:2704 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Memory state around the buggy address: ffff88807d5f9e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807d5f9e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88807d5f9f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88807d5f9f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88807d5fa000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb Fixes: 0dad4087a86a ("tcp/dccp: get rid of inet_twsk_purge()") Signed-off-by: Eric Dumazet Reported-by: syzbot Reported-by: Paolo Abeni Tested-by: Paolo Abeni Link: https://lore.kernel.org/r/20220126180714.845362-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski

dccp: don't duplicate ccid when cloning dccp sock

2021-09-08T10:28:35Z

Commit 2677d2067731 ("dccp: don't free ccid2_hc_tx_sock ...") fixed a UAF but reintroduced CVE-2017-6074. When the sock is cloned, two dccps_hc_tx_ccid will reference to the same ccid. So one can free the ccid object twice from two socks after cloning. This issue was found by "Hadar Manor" as well and assigned with CVE-2020-16119, which was fixed in Ubuntu's kernel. So here I port the patch from Ubuntu to fix it. The patch prevents cloned socks from referencing the same ccid. Fixes: 2677d2067731410 ("dccp: don't free ccid2_hc_tx_sock ...") Signed-off-by: Zhenpeng Lin Signed-off-by: David S. Miller

dccp: Add missing annotation for dccp_child_process()

2020-02-24T21:26:49Z

Sparse reports a warning at dccp_child_process() warning: context imbalance in dccp_child_process() - unexpected unlock The root cause is the missing annotation at dccp_child_process() Add the missing __releases(child) annotation Signed-off-by: Jules Irenge Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32Z

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

net-tcp: remove useless tw_timeout field

2018-06-05T14:45:24Z

Tested: 'git grep tw_timeout' comes up empty and it builds :-) Signed-off-by: Maciej Żenczykowski Cc: Eric Dumazet Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp/dccp: avoid one atomic operation for timewait hashdance

2017-12-13T19:33:10Z

First, rename __inet_twsk_hashdance() to inet_twsk_hashdance() Then, remove one inet_twsk_put() by setting tw_refcnt to 3 instead of 4, but adding a fat warning that we do not have the right to access tw anymore after inet_twsk_hashdance() Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

tcp/dccp: block bh before arming time_wait timer

2017-12-01T20:07:43Z

Maciej Żenczykowski reported some panics in tcp_twsk_destructor() that might be caused by the following bug. timewait timer is pinned to the cpu, because we want to transition timwewait refcount from 0 to 4 in one go, once everything has been initialized. At the time commit ed2e92394589 ("tcp/dccp: fix timewait races in timer handling") was merged, TCP was always running from BH habdler. After commit 5413d1babe8f ("net: do not block BH while processing socket backlog") we definitely can run tcp_time_wait() from process context. We need to block BH in the critical section so that the pinned timer has still its purpose. This bug is more likely to happen under stress and when very small RTO are used in datacenter flows. Fixes: 5413d1babe8f ("net: do not block BH while processing socket backlog") Signed-off-by: Eric Dumazet Reported-by: Maciej Żenczykowski Acked-by: Maciej Żenczykowski Signed-off-by: David S. Miller

dccp: fix use-after-free in dccp_feat_activate_values

2017-03-07T22:15:27Z

Dmitry reported crashes in DCCP stack [1] Problem here is that when I got rid of listener spinlock, I missed the fact that DCCP stores a complex state in struct dccp_request_sock, while TCP does not. Since multiple cpus could access it at the same time, we need to add protection. [1] 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 do_softirq.part.17+0x1e8/0x230 kernel/softirq.c:328 do_softirq kernel/softirq.c:176 [inline] __local_bh_enable_ip+0x1f2/0x200 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+0xbb0/0x23d0 net/ipv6/ip6_output.c:123 ip6_finish_output+0x302/0x960 net/ipv6/ip6_output.c:148 NF_HOOK_COND include/linux/netfilter.h:246 [inline] ip6_output+0x1cb/0x8d0 net/ipv6/ip6_output.c:162 ip6_xmit+0xcdf/0x20d0 include/net/dst.h:501 inet6_csk_xmit+0x320/0x5f0 net/ipv6/inet6_connection_sock.c:179 dccp_transmit_skb+0xb09/0x1120 net/dccp/output.c:141 dccp_xmit_packet+0x215/0x760 net/dccp/output.c:280 dccp_write_xmit+0x168/0x1d0 net/dccp/output.c:362 dccp_sendmsg+0x79c/0xb10 net/dccp/proto.c:796 inet_sendmsg+0x164/0x5b0 net/ipv4/af_inet.c:744 sock_sendmsg_nosec net/socket.c:635 [inline] sock_sendmsg+0xca/0x110 net/socket.c:645 SYSC_sendto+0x660/0x810 net/socket.c:1687 SyS_sendto+0x40/0x50 net/socket.c:1655 entry_SYSCALL_64_fastpath+0x1f/0xc2 RIP: 0033:0x4458b9 RSP: 002b:00007f8ceb77bb58 EFLAGS: 00000282 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000000000000017 RCX: 00000000004458b9 RDX: 0000000000000023 RSI: 0000000020e60000 RDI: 0000000000000017 RBP: 00000000006e1b90 R08: 00000000200f9fe1 R09: 0000000000000020 R10: 0000000000008010 R11: 0000000000000282 R12: 00000000007080a8 R13: 0000000000000000 R14: 00007f8ceb77c9c0 R15: 00007f8ceb77c700 Object at ffff88003713be50, in cache kmalloc-64 size: 64 Allocated: PID = 8446 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+0xad/0xe0 mm/kasan/kasan.c:605 kmem_cache_alloc_trace+0x82/0x270 mm/slub.c:2738 kmalloc include/linux/slab.h:490 [inline] dccp_feat_entry_new+0x214/0x410 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+0x1f1/0xc90 net/dccp/output.c:423 dccp_v6_send_response+0x4ec/0xc20 net/dccp/ipv6.c:217 dccp_v6_conn_request+0xaba/0x11b0 net/dccp/ipv6.c:377 dccp_rcv_state_process+0x51e/0x1650 net/dccp/input.c:606 dccp_v6_do_rcv+0x213/0x350 net/dccp/ipv6.c:632 sk_backlog_rcv include/net/sock.h:893 [inline] __sk_receive_skb+0x36f/0xcc0 net/core/sock.c:479 dccp_v6_rcv+0xba5/0x1d00 net/dccp/ipv6.c:742 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 Freed: PID = 15 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+0x73/0xc0 mm/kasan/kasan.c:578 slab_free_hook mm/slub.c:1355 [inline] slab_free_freelist_hook mm/slub.c:1377 [inline] slab_free mm/slub.c:2954 [inline] kfree+0xe8/0x2b0 mm/slub.c:3874 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/0xab0 net/dccp/feat.c:1543 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 Memory state around the buggy address: ffff88003713bd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88003713bd80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff88003713be00: fc fc fc fc fc fc fc fc fc fc fb fb fb fb fb fb ^ Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table") Signed-off-by: Eric Dumazet Reported-by: Dmitry Vyukov Tested-by: Dmitry Vyukov Signed-off-by: David S. Miller

net: Introduce sk_clone_lock() error path routine

2017-03-02T21:19:33Z

When handling problems in cloning a socket with the sk_clone_locked() function we need to perform several steps that were open coded in it and its callers, so introduce a routine to avoid this duplication: sk_free_unlock_clone(). Cc: Cong Wang Cc: Dmitry Vyukov Cc: Eric Dumazet Cc: Gerrit Renker Cc: Thomas Gleixner Link: http://lkml.kernel.org/n/net-ui6laqkotycunhtmqryl9bfx@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller

dccp: Unlock sock before calling sk_free()

2017-03-02T21:19:33Z

The code where sk_clone() came from created a new socket and locked it, but then, on the error path didn't unlock it. This problem stayed there for a long while, till b0691c8ee7c2 ("net: Unlock sock before calling sk_free()") fixed it, but unfortunately the callers of sk_clone() (now sk_clone_locked()) were not audited and the one in dccp_create_openreq_child() remained. Now in the age of the syskaller fuzzer, this was finally uncovered, as reported by Dmitry: ---- 8< ---- I've got the following report while running syzkaller fuzzer on 86292b33d4b7 ("Merge branch 'akpm' (patches from Andrew)") [ BUG: held lock freed! ] 4.10.0+ #234 Not tainted ------------------------- syz-executor6/6898 is freeing memory ffff88006286cac0-ffff88006286d3b7, with a lock still held there! (slock-AF_INET6){+.-...}, at: [] spin_lock include/linux/spinlock.h:299 [inline] (slock-AF_INET6){+.-...}, at: [] sk_clone_lock+0x3d9/0x12c0 net/core/sock.c:1504 5 locks held by syz-executor6/6898: #0: (sk_lock-AF_INET6){+.+.+.}, at: [] lock_sock include/net/sock.h:1460 [inline] #0: (sk_lock-AF_INET6){+.+.+.}, at: [] inet_stream_connect+0x44/0xa0 net/ipv4/af_inet.c:681 #1: (rcu_read_lock){......}, at: [] inet6_csk_xmit+0x12a/0x5d0 net/ipv6/inet6_connection_sock.c:126 #2: (rcu_read_lock){......}, at: [] __skb_unlink include/linux/skbuff.h:1767 [inline] #2: (rcu_read_lock){......}, at: [] __skb_dequeue include/linux/skbuff.h:1783 [inline] #2: (rcu_read_lock){......}, at: [] process_backlog+0x264/0x730 net/core/dev.c:4835 #3: (rcu_read_lock){......}, at: [] ip6_input_finish+0x0/0x1700 net/ipv6/ip6_input.c:59 #4: (slock-AF_INET6){+.-...}, at: [] spin_lock include/linux/spinlock.h:299 [inline] #4: (slock-AF_INET6){+.-...}, at: [] sk_clone_lock+0x3d9/0x12c0 net/core/sock.c:1504 Fix it just like was done by b0691c8ee7c2 ("net: Unlock sock before calling sk_free()"). Reported-by: Dmitry Vyukov Cc: Cong Wang Cc: Eric Dumazet Cc: Gerrit Renker Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170301153510.GE15145@kernel.org Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller