KASAN: slab-out-of-bounds Read in qfq_reset_qdisc

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 14cfdbd3 Linux 4.19.112
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12bb4813e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=48ea0e0a21a4900f
dashboard link: https://syzkaller.appspot.com/bug?extid=2d94095b24b586050b53
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+2d9409...@syzkaller.appspotmail.com

device veth1_macvtap left promiscuous mode
device veth0_macvtap left promiscuous mode
device veth1_vlan left promiscuous mode
device veth0_vlan left promiscuous mode
==================================================================
BUG: KASAN: slab-out-of-bounds in qfq_reset_qdisc+0x292/0x300 net/sched/sch_qfq.c:1468
Read of size 4 at addr ffff8880a831bbe0 by task kworker/u4:0/26854

CPU: 0 PID: 26854 Comm: kworker/u4:0 Not tainted 4.19.112-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x188/0x20d lib/dump_stack.c:118
print_address_description.cold+0x7c/0x212 mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report mm/kasan/report.c:412 [inline]
kasan_report.cold+0x88/0x2b9 mm/kasan/report.c:396
qfq_reset_qdisc+0x292/0x300 net/sched/sch_qfq.c:1468
qdisc_destroy+0x144/0x6b0 net/sched/sch_generic.c:980
dev_shutdown+0x2b5/0x47a net/sched/sch_generic.c:1300
rollback_registered_many+0x64a/0xc40 net/core/dev.c:8173
unregister_netdevice_many.part.0+0x16/0x1e0 net/core/dev.c:9294
unregister_netdevice_many net/core/dev.c:9293 [inline]
default_device_exit_batch+0x2ff/0x3c0 net/core/dev.c:9765
ops_exit_list.isra.0+0xef/0x140 net/core/net_namespace.c:156
cleanup_net+0x3bf/0x850 net/core/net_namespace.c:553
process_one_work+0x91f/0x1640 kernel/workqueue.c:2155
worker_thread+0x96/0xe20 kernel/workqueue.c:2298
kthread+0x34a/0x420 kernel/kthread.c:246
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 4379:
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc mm/kasan/kasan.c:553 [inline]
kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:531
kmem_cache_alloc_trace+0x14d/0x7a0 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
kobject_create+0x38/0x70 lib/kobject.c:739
kobject_create_and_add+0x16/0x60 lib/kobject.c:765
batadv_sysfs_add_hardif+0x30/0x120 net/batman-adv/sysfs.c:1168
batadv_hardif_add_interface net/batman-adv/hard-interface.c:921 [inline]
batadv_hard_if_event+0xd70/0x14f0 net/batman-adv/hard-interface.c:1038
notifier_call_chain+0xc0/0x230 kernel/notifier.c:93
call_netdevice_notifiers net/core/dev.c:1766 [inline]
register_netdevice+0x9b0/0xf50 net/core/dev.c:8738
veth_newlink+0x400/0x950 drivers/net/veth.c:1143
rtnl_newlink+0xf03/0x1440 net/core/rtnetlink.c:3141
rtnetlink_rcv_msg+0x453/0xaf0 net/core/rtnetlink.c:4777
netlink_rcv_skb+0x160/0x410 net/netlink/af_netlink.c:2455
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x4d7/0x6a0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x80b/0xcd0 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:632
___sys_sendmsg+0x803/0x920 net/socket.c:2115
__sys_sendmsg+0xec/0x1b0 net/socket.c:2153
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8094:
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0xf7/0x140 mm/kasan/kasan.c:521
__cache_free mm/slab.c:3503 [inline]
kfree+0xce/0x220 mm/slab.c:3822
__vunmap+0x2d0/0x3e0 mm/vmalloc.c:1536
vfree+0x65/0x100 mm/vmalloc.c:1597
__do_replace+0x169/0x8a0 net/ipv6/netfilter/ip6_tables.c:1120
do_replace net/ipv6/netfilter/ip6_tables.c:1160 [inline]
do_ip6t_set_ctl+0x2d2/0x425 net/ipv6/netfilter/ip6_tables.c:1684
nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
nf_setsockopt+0x6f/0xc0 net/netfilter/nf_sockopt.c:115
ipv6_setsockopt net/ipv6/ipv6_sockglue.c:944 [inline]
ipv6_setsockopt+0x13c/0x170 net/ipv6/ipv6_sockglue.c:928
tcp_setsockopt net/ipv4/tcp.c:3082 [inline]
tcp_setsockopt+0x86/0xd0 net/ipv4/tcp.c:3076
__sys_setsockopt+0x14d/0x240 net/socket.c:1901
__do_sys_setsockopt net/socket.c:1912 [inline]
__se_sys_setsockopt net/socket.c:1909 [inline]
__x64_sys_setsockopt+0xba/0x150 net/socket.c:1909
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880a831bb80
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 32 bytes to the right of
64-byte region [ffff8880a831bb80, ffff8880a831bbc0)
The buggy address belongs to the page:
page:ffffea0002a0c6c0 count:1 mapcount:0 mapping:ffff88812c3dc340 index:0xffff8880a831ba80
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea00022f3348 ffffea00012f9308 ffff88812c3dc340
raw: ffff8880a831ba80 ffff8880a831b000 0000000100000019 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880a831ba80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8880a831bb00: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff8880a831bb80: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
^
ffff8880a831bc00: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
ffff8880a831bc80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.