KASAN: use-after-free Read in rht_deferred_worker

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2b791501 Linux 4.14.203
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=131a3782500000
kernel config: https://syzkaller.appspot.com/x/.config?x=e52bb6f2a595a463
dashboard link: https://syzkaller.appspot.com/bug?extid=7928f2e8e6db71ec5337
compiler: gcc (GCC) 10.1.0-syz 20200507

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+7928f2...@syzkaller.appspotmail.com

R13: 00007ffe5c62e42f R14: 00007f1f2e7c69c0 R15: 000000000118bf2c
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
==================================================================
CPU: 0 PID: 19126 Comm: syz-executor.4 Not tainted 4.14.203-syzkaller #0
BUG: KASAN: use-after-free in rhashtable_rehash_one lib/rhashtable.c:276 [inline]
BUG: KASAN: use-after-free in rhashtable_rehash_chain lib/rhashtable.c:316 [inline]
BUG: KASAN: use-after-free in rhashtable_rehash_table lib/rhashtable.c:364 [inline]
BUG: KASAN: use-after-free in rht_deferred_worker+0x1366/0x1890 lib/rhashtable.c:465
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Read of size 8 at addr ffff88809dc53300 by task kworker/1:3/7791
Call Trace:

__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x283 lib/dump_stack.c:58
fail_dump lib/fault-inject.c:51 [inline]
should_fail.cold+0x10a/0x154 lib/fault-inject.c:149
should_failslab+0xd6/0x130 mm/failslab.c:32
slab_pre_alloc_hook mm/slab.h:421 [inline]
slab_alloc_node mm/slab.c:3297 [inline]
kmem_cache_alloc_node+0x263/0x410 mm/slab.c:3640
__alloc_skb+0x5c/0x510 net/core/skbuff.c:193
alloc_skb include/linux/skbuff.h:980 [inline]
tfilter_notify+0x89/0x240 net/sched/cls_api.c:472
tc_ctl_tfilter+0x11af/0x1c01 net/sched/cls_api.c:743
rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4316
netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2433
netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1313
netlink_sendmsg+0x62e/0xb80 net/netlink/af_netlink.c:1878
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xb5/0x100 net/socket.c:656
___sys_sendmsg+0x326/0x800 net/socket.c:2062
__sys_sendmmsg+0x129/0x330 net/socket.c:2152
SYSC_sendmmsg net/socket.c:2183 [inline]
SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45deb9
RSP: 002b:00007f1f2e7c5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000027fc0 RCX: 000000000045deb9
RDX: 010efe10675dec16 RSI: 0000000020000200 RDI: 0000000000000003
RBP: 00007f1f2e7c5ca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000006
R13: 00007ffe5c62e42f R14: 00007f1f2e7c69c0 R15: 000000000118bf2c
CPU: 1 PID: 7791 Comm: kworker/1:3 Not tainted 4.14.203-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events rht_deferred_worker
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x283 lib/dump_stack.c:58
print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
kasan_report mm/kasan/report.c:409 [inline]
__asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
rhashtable_rehash_one lib/rhashtable.c:276 [inline]
rhashtable_rehash_chain lib/rhashtable.c:316 [inline]
rhashtable_rehash_table lib/rhashtable.c:364 [inline]
rht_deferred_worker+0x1366/0x1890 lib/rhashtable.c:465
process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 19085:
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618
kmalloc include/linux/slab.h:488 [inline]
kzalloc include/linux/slab.h:661 [inline]
fl_change+0x27e/0x4830 net/sched/cls_flower.c:919
tc_ctl_tfilter+0xb54/0x1c01 net/sched/cls_api.c:738
rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4316
netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2433
netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline]
netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1313
netlink_sendmsg+0x62e/0xb80 net/netlink/af_netlink.c:1878
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xb5/0x100 net/socket.c:656
___sys_sendmsg+0x326/0x800 net/socket.c:2062
__sys_sendmmsg+0x129/0x330 net/socket.c:2152
SYSC_sendmmsg net/socket.c:2183 [inline]
SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 478:
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kfree+0xc9/0x250 mm/slab.c:3815
fl_destroy_filter_work+0x1a/0x20 net/sched/cls_flower.c:234
process_one_work+0x793/0x14a0 kernel/workqueue.c:2116
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

The buggy address belongs to the object at ffff88809dc53300
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
512-byte region [ffff88809dc53300, ffff88809dc53500)
The buggy address belongs to the page:
page:ffffea00027714c0 count:1 mapcount:0 mapping:ffff88809dc53080 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff88809dc53080 0000000000000000 0000000100000006
raw: ffffea000268d6a0 ffffea00028cd7a0 ffff88813fe80940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809dc53200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88809dc53280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809dc53300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809dc53380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809dc53400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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[syzbot]

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