KASAN: use-after-free Read in tcf_action_destroy

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d09b8017 Linux 4.19.147
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14b5d373900000
kernel config: https://syzkaller.appspot.com/x/.config?x=47cc70be3c316a0a
dashboard link: https://syzkaller.appspot.com/bug?extid=49d06b0882526de56315
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1676468d900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13a7ead3900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+49d06b...@syzkaller.appspotmail.com

netlink: 32 bytes leftover after parsing attributes in process `syz-executor703'.
netlink: 32 bytes leftover after parsing attributes in process `syz-executor703'.
netlink: 32 bytes leftover after parsing attributes in process `syz-executor703'.
==================================================================
BUG: KASAN: use-after-free in tcf_action_destroy+0x188/0x1b0 net/sched/act_api.c:655
Read of size 8 at addr ffff88809fad7bc0 by task syz-executor703/6504

CPU: 0 PID: 6504 Comm: syz-executor703 Not tainted 4.19.147-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+0x22c/0x33e lib/dump_stack.c:118
print_address_description.cold+0x56/0x25c mm/kasan/report.c:256
kasan_report_error.cold+0x66/0xb9 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
tcf_action_destroy+0x188/0x1b0 net/sched/act_api.c:655
tcf_action_init+0x2ff/0x490 net/sched/act_api.c:949
tcf_action_add+0xd9/0x360 net/sched/act_api.c:1314
tc_ctl_action+0x337/0x417 net/sched/act_api.c:1369
rtnetlink_rcv_msg+0x498/0xc10 net/core/rtnetlink.c:4778
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x717/0xcc0 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xc7/0x130 net/socket.c:632
___sys_sendmsg+0x7bb/0x8f0 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+0xf9/0x670 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446d29
Code: e8 0c e8 ff ff 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 db 06 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fc5afe92d98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000446d29
RDX: 0000000000000000 RSI: 0000000020002980 RDI: 0000000000000003
RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c
R13: 0001008400000000 R14: 0000000000000000 R15: 053b003000000098

Allocated by task 6503:
__do_kmalloc mm/slab.c:3727 [inline]
__kmalloc+0x15a/0x4f0 mm/slab.c:3736
kmalloc include/linux/slab.h:520 [inline]
kzalloc include/linux/slab.h:709 [inline]
tcf_idr_create+0x5b/0x650 net/sched/act_api.c:361
tcf_connmark_init+0x4f3/0x7fa net/sched/act_connmark.c:127
tcf_action_init_1+0x962/0xc40 net/sched/act_api.c:870
tcf_action_init+0x2c3/0x490 net/sched/act_api.c:933
tcf_action_add+0xd9/0x360 net/sched/act_api.c:1314
tc_ctl_action+0x337/0x417 net/sched/act_api.c:1369
rtnetlink_rcv_msg+0x498/0xc10 net/core/rtnetlink.c:4778
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x717/0xcc0 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xc7/0x130 net/socket.c:632
___sys_sendmsg+0x7bb/0x8f0 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+0xf9/0x670 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 6524:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x250 mm/slab.c:3822
__tcf_action_put+0xf4/0x130 net/sched/act_api.c:112
__tcf_idr_release net/sched/act_api.c:142 [inline]
__tcf_idr_release net/sched/act_api.c:122 [inline]
tcf_del_walker net/sched/act_api.c:266 [inline]
tcf_generic_walker+0x62d/0xa20 net/sched/act_api.c:292
tca_action_flush net/sched/act_api.c:1142 [inline]
tca_action_gd+0x95f/0x1720 net/sched/act_api.c:1248
tc_ctl_action+0x27d/0x417 net/sched/act_api.c:1377
rtnetlink_rcv_msg+0x498/0xc10 net/core/rtnetlink.c:4778
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2455
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x717/0xcc0 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xc7/0x130 net/socket.c:632
___sys_sendmsg+0x7bb/0x8f0 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+0xf9/0x670 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809fad7bc0
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 0 bytes inside of
256-byte region [ffff88809fad7bc0, ffff88809fad7cc0)
The buggy address belongs to the page:
page:ffffea00027eb5c0 count:1 mapcount:0 mapping:ffff88812c3f67c0 index:0xffff88809fad7e40
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffffea00027e3c88 ffffea00027f3648 ffff88812c3f67c0
raw: ffff88809fad7e40 ffff88809fad7080 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809fad7a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809fad7b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809fad7b80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
^
ffff88809fad7c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809fad7c80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================


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