[syzbot] possible deadlock in release_sock

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 87b93b678e95 octeontx2-pf: Avoid use of GFP_KERNEL in atom..
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=1032dd91480000
kernel config: https://syzkaller.appspot.com/x/.config?x=2b6ecad960fc703e
dashboard link: https://syzkaller.appspot.com/bug?extid=bbd35b345c7cab0d9a08
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1716b3a1480000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14e57a91480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/191e8cc30fff/disk-87b93b67.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d34dd6d2fffd/vmlinux-87b93b67.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ad9344e76aaf/bzImage-87b93b67.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bbd35b...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.2.0-rc3-syzkaller-00197-g87b93b678e95 #0 Not tainted
------------------------------------------------------
syz-executor131/5064 is trying to acquire lock:
ffff888017b6b370 (slock-AF_INET){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:355 [inline]
ffff888017b6b370 (slock-AF_INET){+.-.}-{2:2}, at: release_sock+0x1f/0x1b0 net/core/sock.c:3483

but task is already holding lock:
ffff888017b6b678 (clock-AF_INET){++..}-{2:2}, at: l2tp_tunnel_register+0x2be/0x11e0 net/l2tp/l2tp_core.c:1484

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (clock-AF_INET){++..}-{2:2}:
__raw_read_lock_bh include/linux/rwlock_api_smp.h:176 [inline]
_raw_read_lock_bh+0x3f/0x70 kernel/locking/spinlock.c:252
sock_i_uid+0x1f/0xb0 net/core/sock.c:2564
sk_reuseport_match net/ipv4/inet_connection_sock.c:401 [inline]
inet_csk_get_port+0x85f/0x2660 net/ipv4/inet_connection_sock.c:532
inet_csk_listen_start+0x1ad/0x440 net/ipv4/inet_connection_sock.c:1237
inet_listen+0x235/0x640 net/ipv4/af_inet.c:228
__sys_listen+0x181/0x250 net/socket.c:1810
__do_sys_listen net/socket.c:1819 [inline]
__se_sys_listen net/socket.c:1817 [inline]
__x64_sys_listen+0x54/0x80 net/socket.c:1817
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (&tcp_hashinfo.bhash[i].lock){+.-.}-{2:2}:
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
__inet_inherit_port+0x2b5/0x1840 net/ipv4/inet_hashtables.c:230
tcp_v4_syn_recv_sock+0xb5b/0x1450 net/ipv4/tcp_ipv4.c:1628
tcp_check_req+0x632/0x1aa0 net/ipv4/tcp_minisocks.c:803
tcp_v4_rcv+0x2120/0x3280 net/ipv4/tcp_ipv4.c:2070
ip_protocol_deliver_rcu+0x9f/0x460 net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x2ec/0x4c0 net/ipv4/ip_input.c:233
NF_HOOK include/linux/netfilter.h:302 [inline]
NF_HOOK include/linux/netfilter.h:296 [inline]
ip_local_deliver+0x1ae/0x200 net/ipv4/ip_input.c:254
dst_input include/net/dst.h:454 [inline]
ip_sublist_rcv_finish+0x9a/0x2c0 net/ipv4/ip_input.c:580
ip_list_rcv_finish net/ipv4/ip_input.c:630 [inline]
ip_sublist_rcv+0x533/0x980 net/ipv4/ip_input.c:638
ip_list_rcv+0x31e/0x470 net/ipv4/ip_input.c:673
__netif_receive_skb_list_ptype net/core/dev.c:5525 [inline]
__netif_receive_skb_list_core+0x548/0x8f0 net/core/dev.c:5573
__netif_receive_skb_list net/core/dev.c:5625 [inline]
netif_receive_skb_list_internal+0x75f/0xd90 net/core/dev.c:5716
gro_normal_list include/net/gro.h:433 [inline]
gro_normal_list include/net/gro.h:429 [inline]
napi_complete_done+0x243/0x960 net/core/dev.c:6056
virtqueue_napi_complete drivers/net/virtio_net.c:405 [inline]
virtnet_poll+0xd08/0x1300 drivers/net/virtio_net.c:1682
__napi_poll+0xb8/0x770 net/core/dev.c:6485
napi_poll net/core/dev.c:6552 [inline]
net_rx_action+0xa00/0xde0 net/core/dev.c:6663
__do_softirq+0x1fb/0xadc kernel/softirq.c:571
invoke_softirq kernel/softirq.c:445 [inline]
__irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
irq_exit_rcu+0x9/0x20 kernel/softirq.c:662
sysvec_apic_timer_interrupt+0x97/0xc0 arch/x86/kernel/apic/apic.c:1107
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:649
native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
acpi_safe_halt drivers/acpi/processor_idle.c:112 [inline]
acpi_idle_do_entry+0x1fd/0x2a0 drivers/acpi/processor_idle.c:570
acpi_idle_enter+0x368/0x510 drivers/acpi/processor_idle.c:707
cpuidle_enter_state+0x1af/0xd40 drivers/cpuidle/cpuidle.c:239
cpuidle_enter+0x4e/0xa0 drivers/cpuidle/cpuidle.c:356
call_cpuidle kernel/sched/idle.c:155 [inline]
cpuidle_idle_call kernel/sched/idle.c:236 [inline]
do_idle+0x3f7/0x590 kernel/sched/idle.c:303
cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:400
start_secondary+0x256/0x300 arch/x86/kernel/smpboot.c:264
secondary_startup_64_no_verify+0xce/0xdb

-> #0 (slock-AF_INET){+.-.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:355 [inline]
release_sock+0x1f/0x1b0 net/core/sock.c:3483
l2tp_tunnel_register+0x3db/0x11e0 net/l2tp/l2tp_core.c:1487
l2tp_nl_cmd_tunnel_create+0x3d6/0x8b0 net/l2tp/l2tp_netlink.c:245
genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968
genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065
netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xd3/0x120 net/socket.c:734
____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
__sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
slock-AF_INET --> &tcp_hashinfo.bhash[i].lock --> clock-AF_INET

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(clock-AF_INET);
lock(&tcp_hashinfo.bhash[i].lock);
lock(clock-AF_INET);
lock(slock-AF_INET);

*** DEADLOCK ***

4 locks held by syz-executor131/5064:
#0: ffffffff8e159a10 (cb_lock){++++}-{3:3}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1075
#1: ffffffff8e159ac8 (genl_mutex){+.+.}-{3:3}, at: genl_lock net/netlink/genetlink.c:33 [inline]
#1: ffffffff8e159ac8 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg+0x51a/0x7e0 net/netlink/genetlink.c:1063
#2: ffff888017b6b3f0 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1725 [inline]
#2: ffff888017b6b3f0 (sk_lock-AF_INET){+.+.}-{0:0}, at: l2tp_tunnel_register+0x2aa/0x11e0 net/l2tp/l2tp_core.c:1483
#3: ffff888017b6b678 (clock-AF_INET){++..}-{2:2}, at: l2tp_tunnel_register+0x2be/0x11e0 net/l2tp/l2tp_core.c:1484

stack backtrace:
CPU: 0 PID: 5064 Comm: syz-executor131 Not tainted 6.2.0-rc3-syzkaller-00197-g87b93b678e95 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain kernel/locking/lockdep.c:3831 [inline]
__lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
lock_acquire kernel/locking/lockdep.c:5668 [inline]
lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:355 [inline]
release_sock+0x1f/0x1b0 net/core/sock.c:3483
l2tp_tunnel_register+0x3db/0x11e0 net/l2tp/l2tp_core.c:1487
l2tp_nl_cmd_tunnel_create+0x3d6/0x8b0 net/l2tp/l2tp_netlink.c:245
genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968
genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065
netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xd3/0x120 net/socket.c:734
____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
__sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f82e5a4fbe9
Code: 28 c3 e8 5a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007


---
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[Eric Dumazet]

On Tue, Jan 17, 2023 at 11:59 AM syzbot
<syzbot+bbd35b...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 87b93b678e95 octeontx2-pf: Avoid use of GFP_KERNEL in atom..
> git tree: net
> console output: https://syzkaller.appspot.com/x/log.txt?x=1032dd91480000
> kernel config: https://syzkaller.appspot.com/x/.config?x=2b6ecad960fc703e
> dashboard link: https://syzkaller.appspot.com/bug?extid=bbd35b345c7cab0d9a08
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1716b3a1480000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14e57a91480000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/191e8cc30fff/disk-87b93b67.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/d34dd6d2fffd/vmlinux-87b93b67.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/ad9344e76aaf/bzImage-87b93b67.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+bbd35b...@syzkaller.appspotmail.com

Fix under review :
https://patchwork.kernel.org/project/netdevbpf/patch/20230117110131.1...@google.com/

[syzbot]

syzbot has bisected this issue to:

commit 0b2c59720e65885a394a017d0cf9cab118914682
Author: Cong Wang <cong...@bytedance.com>
Date: Sat Jan 14 03:01:37 2023 +0000

l2tp: close all race conditions in l2tp_tunnel_register()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15331c61480000
start commit: 87b93b678e95 octeontx2-pf: Avoid use of GFP_KERNEL in atom..
git tree: net
final oops: https://syzkaller.appspot.com/x/report.txt?x=17331c61480000
console output: https://syzkaller.appspot.com/x/log.txt?x=13331c61480000

kernel config: https://syzkaller.appspot.com/x/.config?x=2b6ecad960fc703e
dashboard link: https://syzkaller.appspot.com/bug?extid=bbd35b345c7cab0d9a08

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1716b3a1480000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14e57a91480000

Reported-by: syzbot+bbd35b...@syzkaller.appspotmail.com
Fixes: 0b2c59720e65 ("l2tp: close all race conditions in l2tp_tunnel_register()")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection