syzbot

netlink: 32 bytes leftover after parsing attributes in process `syz-executor795'.
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BUG: KASAN: use-after-free in tcf_action_destroy+0x188/0x1b0 net/sched/act_api.c:724
Read of size 8 at addr ffff88809ee75400 by task syz-executor795/6876

CPU: 1 PID: 6876 Comm: syz-executor795 Not tainted 5.9.0-rc8-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+0x198/0x1fd lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 tcf_action_destroy+0x188/0x1b0 net/sched/act_api.c:724
 tcf_action_init+0x29c/0x3d0 net/sched/act_api.c:1058
 tcf_action_add+0xd9/0x360 net/sched/act_api.c:1451
 tc_ctl_action+0x33a/0x439 net/sched/act_api.c:1504
 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5563
 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2407
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x445d79
Code: e8 bc b7 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 ab 11 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f6a74b28d98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000006dac28 RCX: 0000000000445d79
RDX: 0000000000000000 RSI: 0000000020002980 RDI: 0000000000000003
RBP: 00000000006dac20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac2c
R13: 0001008400000000 R14: 0000000000000000 R15: 053b003000000098

Allocated by task 6876:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:461
 __do_kmalloc mm/slab.c:3659 [inline]
 __kmalloc+0x1b0/0x360 mm/slab.c:3668
 kmalloc include/linux/slab.h:559 [inline]
 kzalloc include/linux/slab.h:666 [inline]
 tcf_idr_create+0x5b/0x800 net/sched/act_api.c:408
 tcf_connmark_init+0x535/0x960 net/sched/act_connmark.c:126
 tcf_action_init_1+0x6a5/0xac0 net/sched/act_api.c:984
 tcf_action_init+0x260/0x3d0 net/sched/act_api.c:1043
 tcf_action_add+0xd9/0x360 net/sched/act_api.c:1451
 tc_ctl_action+0x33a/0x439 net/sched/act_api.c:1504
 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5563
 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2407
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 6878:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:48
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:56
 kasan_set_free_info+0x1b/0x30 mm/kasan/generic.c:355
 __kasan_slab_free+0xd8/0x120 mm/kasan/common.c:422
 __cache_free mm/slab.c:3422 [inline]
 kfree+0x10e/0x2b0 mm/slab.c:3760
 tcf_idr_release_unsafe net/sched/act_api.c:284 [inline]
 tcf_del_walker net/sched/act_api.c:310 [inline]
 tcf_generic_walker+0x959/0xb60 net/sched/act_api.c:339
 tca_action_flush+0x42b/0x920 net/sched/act_api.c:1278
 tca_action_gd+0x8c9/0xe20 net/sched/act_api.c:1385
 tc_ctl_action+0x280/0x439 net/sched/act_api.c:1512
 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5563
 netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2353
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2407
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2440
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88809ee75400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
 512-byte region [ffff88809ee75400, ffff88809ee75600)
The buggy address belongs to the page:
page:000000004cb01f57 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9ee75
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea000287eec8 ffffea0002974108 ffff8880aa040600
raw: 0000000000000000 ffff88809ee75000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809ee75300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809ee75380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809ee75400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88809ee75480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809ee75500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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