WARNING in cbq_destroy_class

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: d183c8e2 Linux 4.19.98
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1725a985e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=270360e13b071d92
dashboard link: https://syzkaller.appspot.com/bug?extid=eb72a2e94c3d00901d39
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1370e185e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=173f4d85e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+eb72a2...@syzkaller.appspotmail.com

SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=8204 comm=syz-executor212
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=8204 comm=syz-executor212
netlink: 96 bytes leftover after parsing attributes in process `syz-executor212'.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 8207 at net/sched/sch_cbq.c:1439 cbq_destroy_class.cold+0x11/0x18 net/sched/sch_cbq.c:1439
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 8207 Comm: syz-executor212 Not tainted 4.19.98-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
panic+0x26a/0x50e kernel/panic.c:186
__warn.cold+0x20/0x53 kernel/panic.c:541
report_bug+0x263/0x2b0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
fixup_bug arch/x86/kernel/traps.c:173 [inline]
do_error_trap+0x204/0x360 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1037
RIP: 0010:cbq_destroy_class.cold+0x11/0x18 net/sched/sch_cbq.c:1439
Code: c0 fb e9 82 fe ff ff 4c 89 f7 e8 7a 9e c0 fb e9 26 ff ff ff e9 76 02 00 00 e8 4b 04 89 fb 48 c7 c7 a0 9a 4d 88 e8 d3 67 73 fb <0f> 0b e9 90 59 ff ff 4c 8d 6b 68 e8 2f 04 89 fb 48 89 d8 48 c1 e8
RSP: 0018:ffff888093dd7178 EFLAGS: 00010282
RAX: 0000000000000024 RBX: ffff88808ed2cdc0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff81558b76 RDI: ffffed10127bae21
RBP: ffff888093dd7190 R08: 0000000000000024 R09: ffffed1015d05079
R10: ffffed1015d05078 R11: ffff8880ae8283c7 R12: ffff88808ed2d0a0
R13: 0000000000000001 R14: 0000000000000000 R15: ffff88808ed2d0a0
cbq_destroy net/sched/sch_cbq.c:1473 [inline]
cbq_destroy+0x208/0x2c0 net/sched/sch_cbq.c:1449
qdisc_destroy+0x18a/0x6b0 net/sched/sch_generic.c:982
notify_and_destroy+0xa2/0xb0 net/sched/sch_api.c:924
qdisc_graft+0x4f3/0x1030 net/sched/sch_api.c:991
tc_modify_qdisc+0xcae/0x1bd3 net/sched/sch_api.c:1582
rtnetlink_rcv_msg+0x463/0xb00 net/core/rtnetlink.c:4768
netlink_rcv_skb+0x17d/0x460 net/netlink/af_netlink.c:2454
rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:4786
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x53a/0x730 net/netlink/af_netlink.c:1343
netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1908
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xd7/0x130 net/socket.c:632
kernel_sendmsg+0x44/0x50 net/socket.c:640
sock_no_sendpage+0x116/0x150 net/core/sock.c:2642
kernel_sendpage+0x92/0xf0 net/socket.c:3378
sock_sendpage+0x8b/0xc0 net/socket.c:847
pipe_to_sendpage+0x296/0x360 fs/splice.c:452
splice_from_pipe_feed fs/splice.c:503 [inline]
__splice_from_pipe+0x391/0x7d0 fs/splice.c:627
splice_from_pipe+0x108/0x170 fs/splice.c:662
generic_splice_sendpage+0x3c/0x50 fs/splice.c:833
do_splice_from fs/splice.c:852 [inline]
do_splice+0x642/0x1340 fs/splice.c:1154
__do_sys_splice fs/splice.c:1428 [inline]
__se_sys_splice fs/splice.c:1408 [inline]
__x64_sys_splice+0x2c6/0x330 fs/splice.c:1408
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446e79
Code: e8 5c b3 02 00 48 83 c4 18 c3 0f 1f 80 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 0f 83 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f15b795ed88 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00000000006dcc98 RCX: 0000000000446e79
RDX: 0000000000000009 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 00000000006dcc90 R08: 000000000004ffe0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc9c
R13: 00000000004aed8e R14: 54c6c2ff093a6d32 R15: 0000000000010000
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 8bac5040 Linux 4.14.167
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11b81611e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=ed52db44a31a52da
dashboard link: https://syzkaller.appspot.com/bug?extid=2d67293d34132df6c5b8

compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=135cdb66e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=103d0376e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:

Reported-by: syzbot+2d6729...@syzkaller.appspotmail.com

SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=7258 comm=syz-executor281
SELinux: unrecognized netlink message: protocol=0 nlmsg_type=0 sclass=netlink_route_socket pig=7258 comm=syz-executor281
netlink: 96 bytes leftover after parsing attributes in process `syz-executor281'.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7261 at net/sched/sch_cbq.c:1428 cbq_destroy_class+0x10b/0x140 net/sched/sch_cbq.c:1428

Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 7261 Comm: syz-executor281 Not tainted 4.14.167-syzkaller #0

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

__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x142/0x197 lib/dump_stack.c:58
panic+0x1f9/0x42d kernel/panic.c:183
__warn.cold+0x2f/0x2f kernel/panic.c:547
report_bug+0x216/0x254 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:177 [inline]
fixup_bug arch/x86/kernel/traps.c:172 [inline]
do_error_trap+0x1bb/0x310 arch/x86/kernel/traps.c:295
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963
RIP: 0010:cbq_destroy_class+0x10b/0x140 net/sched/sch_cbq.c:1428
RSP: 0018:ffff88809ba77340 EFLAGS: 00010297
RAX: ffff888084ff0340 RBX: ffff8880a54a0ec0 RCX: 1ffff110109fe181
RDX: 0000000000000000 RSI: ffff8880a54a10e0 RDI: ffff8880a54a1200
RBP: ffff88809ba77350 R08: ffff888084ff0340 R09: ffff888084ff0c08
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a54a10e0
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8880a54a10e0
cbq_destroy net/sched/sch_cbq.c:1462 [inline]
cbq_destroy+0x1ed/0x290 net/sched/sch_cbq.c:1438
qdisc_destroy+0x148/0x320 net/sched/sch_generic.c:725
notify_and_destroy+0xa2/0xb0 net/sched/sch_api.c:885
qdisc_graft+0x36f/0xd00 net/sched/sch_api.c:949
tc_modify_qdisc+0xa5e/0x1272 net/sched/sch_api.c:1446
rtnetlink_rcv_msg+0x3da/0xb70 net/core/rtnetlink.c:4306
netlink_rcv_skb+0x14f/0x3c0 net/netlink/af_netlink.c:2432
rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:4318
netlink_unicast_kernel net/netlink/af_netlink.c:1286 [inline]
netlink_unicast+0x44d/0x650 net/netlink/af_netlink.c:1312
netlink_sendmsg+0x7c4/0xc60 net/netlink/af_netlink.c:1877
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xce/0x110 net/socket.c:656
kernel_sendmsg+0x44/0x50 net/socket.c:664
sock_no_sendpage+0x107/0x130 net/core/sock.c:2569
kernel_sendpage+0x92/0xf0 net/socket.c:3407
sock_sendpage+0x8b/0xc0 net/socket.c:871
pipe_to_sendpage+0x242/0x340 fs/splice.c:451
splice_from_pipe_feed fs/splice.c:502 [inline]
__splice_from_pipe+0x348/0x780 fs/splice.c:626
splice_from_pipe+0xf0/0x150 fs/splice.c:661
generic_splice_sendpage+0x3c/0x50 fs/splice.c:832
do_splice_from fs/splice.c:851 [inline]
do_splice fs/splice.c:1147 [inline]
SYSC_splice fs/splice.c:1402 [inline]
SyS_splice+0xd92/0x1430 fs/splice.c:1382
do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x446e79
RSP: 002b:00007f54f839bd88 EFLAGS: 00000246 ORIG_RAX: 0000000000000113

[syzbot]

syzbot suspects this bug was fixed by commit:

commit 9f7a32834b624bdfc94a21f3035463310faf7259
Author: Cong Wang <xiyou.w...@gmail.com>
Date: Fri Jan 24 00:26:18 2020 +0000

net_sched: fix ops->bind_class() implementations

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12c77de9e00000
start commit: d183c8e2 Linux 4.19.98
git tree: linux-4.19.y

kernel config: https://syzkaller.appspot.com/x/.config?x=270360e13b071d92
dashboard link: https://syzkaller.appspot.com/bug?extid=eb72a2e94c3d00901d39

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1370e185e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=173f4d85e00000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: net_sched: fix ops->bind_class() implementations

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