BUG: soft lockup in netlink_sendmsg

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2034d6f0 Linux 4.19.184
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17e8e986d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=42af7daace4bc0cc
dashboard link: https://syzkaller.appspot.com/bug?extid=e1d9f8a36ecb96e1faaf

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e1d9f8...@syzkaller.appspotmail.com

nf_conntrack: default automatic helper assignment has been turned off for security reasons and CT-based firewall rule not found. Use the iptables CT target to attach helpers instead.
IPVS: ftp: loaded support on port[0] = 21
watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz-executor.2:14482]
Modules linked in:
irq event stamp: 285485
hardirqs last enabled at (285484): [<ffffffff815471c5>] seqcount_lockdep_reader_access include/linux/seqlock.h:83 [inline]
hardirqs last enabled at (285484): [<ffffffff815471c5>] read_seqcount_begin include/linux/seqlock.h:164 [inline]
hardirqs last enabled at (285484): [<ffffffff815471c5>] ktime_get+0x235/0x2f0 kernel/time/timekeeping.c:756
hardirqs last disabled at (285485): [<ffffffff81003d00>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last enabled at (72): [<ffffffff869fd8d6>] netlink_insert+0x156/0x11d0 net/netlink/af_netlink.c:603
softirqs last disabled at (80): [<ffffffff86759742>] __dev_queue_xmit+0x1e2/0x2e00 net/core/dev.c:3773
CPU: 0 PID: 14482 Comm: syz-executor.2 Not tainted 4.19.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__read_once_size include/linux/compiler.h:261 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:69 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x1c/0x50 kernel/kcov.c:101
Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 48 8b 34 24 65 48 8b 04 25 80 df 01 00 65 8b 15 9c 81 9f 7e 81 e2 00 01 1f 00 75 2b <8b> 90 60 13 00 00 83 fa 02 75 20 48 8b 88 68 13 00 00 8b 80 64 13
RSP: 0018:ffff88809c08f628 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: ffff888049840500 RBX: 00000000000010f8 RCX: ffffffff869786ba
RDX: 0000000000000000 RSI: ffffffff869786cc RDI: 0000000000000005
RBP: 000000000000087b R08: ffffffff8c663018 R09: 0000000000001fff
R10: 0000000000000005 R11: ffffffff8c66301b R12: ffff888042e40bc0
R13: 00000000000010f7 R14: 0000000000000000 R15: dffffc0000000000
FS: 00007f2198e1c700(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2198e1c718 CR3: 000000003a9fb000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
cake_heapify+0x14c/0x340 net/sched/sch_cake.c:1379
cake_drop net/sched/sch_cake.c:1468 [inline]
cake_enqueue+0x1296/0x33d0 net/sched/sch_cake.c:1844
__dev_xmit_skb net/core/dev.c:3494 [inline]
__dev_queue_xmit+0x140a/0x2e00 net/core/dev.c:3807
__netlink_deliver_tap_skb net/netlink/af_netlink.c:303 [inline]
__netlink_deliver_tap net/netlink/af_netlink.c:321 [inline]
netlink_deliver_tap+0x8fb/0xb00 net/netlink/af_netlink.c:334
netlink_deliver_tap_kernel net/netlink/af_netlink.c:343 [inline]
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x545/0x690 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:632
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
__sys_sendmsg net/socket.c:2153 [inline]
__do_sys_sendmsg net/socket.c:2162 [inline]
__se_sys_sendmsg net/socket.c:2160 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2198e1c188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000466459
RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000006
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007ffc07b2476f R14: 00007f2198e1c300 R15: 0000000000022000
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60


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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 2034d6f0 Linux 4.19.184
git tree: linux-4.19.y

console output: https://syzkaller.appspot.com/x/log.txt?x=11605b26d00000

kernel config: https://syzkaller.appspot.com/x/.config?x=42af7daace4bc0cc
dashboard link: https://syzkaller.appspot.com/bug?extid=e1d9f8a36ecb96e1faaf

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16754611d00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1063990ed00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e1d9f8...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_CHANGE): batadv_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz-executor970:8348]
Modules linked in:
irq event stamp: 293077
hardirqs last enabled at (293076): [<ffffffff815471c5>] seqcount_lockdep_reader_access include/linux/seqlock.h:83 [inline]
hardirqs last enabled at (293076): [<ffffffff815471c5>] read_seqcount_begin include/linux/seqlock.h:164 [inline]
hardirqs last enabled at (293076): [<ffffffff815471c5>] ktime_get+0x235/0x2f0 kernel/time/timekeeping.c:756
hardirqs last disabled at (293077): [<ffffffff81003d00>] trace_hardirqs_off_thunk+0x1a/0x1c
softirqs last enabled at (60): [<ffffffff869fd8d6>] netlink_insert+0x156/0x11d0 net/netlink/af_netlink.c:603
softirqs last disabled at (68): [<ffffffff86759742>] __dev_queue_xmit+0x1e2/0x2e00 net/core/dev.c:3773
CPU: 0 PID: 8348 Comm: syz-executor970 Not tainted 4.19.184-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

RIP: 0010:cake_heapify+0x2cd/0x340 net/sched/sch_cake.c:1403
Code: e8 38 d5 ca fa 44 0f b7 6c 24 06 89 ee 44 89 ef e8 18 d6 ca fa 41 39 ed 0f 85 45 fe ff ff 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e <41> 5f e9 0c d5 ca fa e8 b7 95 00 fb e9 fc fd ff ff e8 1d 95 00 fb
RSP: 0018:ffff888095f07670 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: ffff8880922b07c0 RCX: ffffffff86978838
RDX: 0000000000000932 RSI: ffff8880ade9e0c0 RDI: 0000000000000004
RBP: dffffc0000000000 R08: ffffffff8c663018 R09: 0000000000000932
R10: 0000000000000004 R11: ffffffff8c66301b R12: 0000000000000931
R13: 0000000000000300 R14: ffff88808a800180 R15: dffffc0000000000
FS: 00007fef04876700(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000000000000000 CR3: 00000000a18d4000 CR4: 00000000001406f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:

cake_drop net/sched/sch_cake.c:1468 [inline]
cake_enqueue+0x1296/0x33d0 net/sched/sch_cake.c:1844
__dev_xmit_skb net/core/dev.c:3494 [inline]
__dev_queue_xmit+0x140a/0x2e00 net/core/dev.c:3807
__netlink_deliver_tap_skb net/netlink/af_netlink.c:303 [inline]
__netlink_deliver_tap net/netlink/af_netlink.c:321 [inline]
netlink_deliver_tap+0x8fb/0xb00 net/netlink/af_netlink.c:334
netlink_deliver_tap_kernel net/netlink/af_netlink.c:343 [inline]
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x545/0x690 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x6bb/0xc40 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:632
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2115
__sys_sendmsg net/socket.c:2153 [inline]
__do_sys_sendmsg net/socket.c:2162 [inline]
__se_sys_sendmsg net/socket.c:2160 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2160
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

RIP: 0033:0x4519b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 18 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fef04876318 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004d04d8 RCX: 00000000004519b9
RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000005
RBP: 00000000004d04d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000049f7f0
R13: 00007ffc1b725baf R14: 00007fef04876400 R15: 0000000000022000