KASAN: use-after-free Read in tcf_exts_destroy

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4edbf74132a4 Linux 4.14.294
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15b53498880000
kernel config: https://syzkaller.appspot.com/x/.config?x=94d4cf9c4e23980f
dashboard link: https://syzkaller.appspot.com/bug?extid=eb33fdb680d76712f241
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

Downloadable assets:
disk image: https://storage.googleapis.com/b40da19b4827/disk-4edbf741.raw.xz
vmlinux: https://storage.googleapis.com/a36e39677c18/vmlinux-4edbf741.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eb33fd...@syzkaller.appspotmail.com

FAT-fs (loop5): Can't find a valid FAT filesystem
==================================================================
BUG: KASAN: use-after-free in tcf_exts_to_list include/net/pkt_cls.h:150 [inline]
BUG: KASAN: use-after-free in tcf_exts_destroy+0x280/0x2f0 net/sched/cls_api.c:897
Read of size 4 at addr ffff88804c280144 by task kworker/u4:3/324

CPU: 0 PID: 324 Comm: kworker/u4:3 Not tainted 4.14.294-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Workqueue: tc_filter_workqueue tcindex_destroy_rexts_work
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
kasan_report mm/kasan/report.c:409 [inline]
__asan_report_load4_noabort+0x68/0x70 mm/kasan/report.c:429
tcf_exts_to_list include/net/pkt_cls.h:150 [inline]
tcf_exts_destroy+0x280/0x2f0 net/sched/cls_api.c:897
__tcindex_destroy_rexts+0x12/0x70 net/sched/cls_tcindex.c:144
tcindex_destroy_rexts_work+0x17/0x20 net/sched/cls_tcindex.c:154
process_one_work+0x793/0x14a0 kernel/workqueue.c:2117
worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 10353:
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
__do_kmalloc mm/slab.c:3720 [inline]
__kmalloc+0x15a/0x400 mm/slab.c:3729
kmalloc_array include/linux/slab.h:607 [inline]
kcalloc include/linux/slab.h:618 [inline]
tcindex_alloc_perfect_hash+0x53/0x3c0 net/sched/cls_tcindex.c:299
tcindex_set_parms+0x13fd/0x17c0 net/sched/cls_tcindex.c:428
tcindex_change+0x1c1/0x2c0 net/sched/cls_tcindex.c:539
tc_ctl_tfilter+0xb54/0x1c10 net/sched/cls_api.c:738
rtnetlink_rcv_msg+0x3be/0xb10 net/core/rtnetlink.c:4322
netlink_rcv_skb+0x125/0x390 net/netlink/af_netlink.c:2454
netlink_unicast_kernel net/netlink/af_netlink.c:1296 [inline]
netlink_unicast+0x437/0x610 net/netlink/af_netlink.c:1322
netlink_sendmsg+0x648/0xbc0 net/netlink/af_netlink.c:1893
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xb5/0x100 net/socket.c:656
___sys_sendmsg+0x6c8/0x800 net/socket.c:2062
__sys_sendmsg+0xa3/0x120 net/socket.c:2096
SYSC_sendmsg net/socket.c:2107 [inline]
SyS_sendmsg+0x27/0x40 net/socket.c:2103
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 8370:
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
__tcindex_destroy+0x2e/0x70 net/sched/cls_tcindex.c:253
__rcu_reclaim kernel/rcu/rcu.h:195 [inline]
rcu_do_batch kernel/rcu/tree.c:2699 [inline]
invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
__rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
rcu_process_callbacks+0x780/0x1180 kernel/rcu/tree.c:2946
__do_softirq+0x24d/0x9ff kernel/softirq.c:288

The buggy address belongs to the object at ffff88804c280140
which belongs to the cache kmalloc-262144 of size 262144
The buggy address is located 4 bytes inside of
262144-byte region [ffff88804c280140, ffff88804c2c0140)
The buggy address belongs to the page:
page:ffffea000130a000 count:1 mapcount:0 mapping:ffff88804c280140 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffff88804c280140 0000000000000000 0000000100000001
raw: ffffea0002b88020 ffff88813fe66048 ffff88813fe65800 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88804c280000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88804c280080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88804c280100: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
^
ffff88804c280180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88804c280200: 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.