KASAN: use-after-free Read in tcf_block_put (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1081814cb00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=37b40cc42924366ae263
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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+37b40c...@syzkaller.appspotmail.com

2097051 pages RAM
0 pages HighMem/MovableOnly
369649 pages reserved
0 pages cma reserved
==================================================================
BUG: KASAN: use-after-free in tcf_block_put+0xf6/0x100 net/sched/cls_api.c:797
Read of size 8 at addr ffff888054ea84a0 by task syz-executor.0/12384

CPU: 1 PID: 12384 Comm: syz-executor.0 Not tainted 4.19.211-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+0x1fc/0x2ef lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1b9 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_block_put+0xf6/0x100 net/sched/cls_api.c:797
cake_destroy+0x3f/0x80 net/sched/sch_cake.c:2634
qdisc_create+0xb70/0x1130 net/sched/sch_api.c:1204
tc_modify_qdisc+0x50d/0x1a80 net/sched/sch_api.c:1572
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x3b3/0x8e0 net/socket.c:2227
__sys_sendmmsg+0x195/0x470 net/socket.c:2322
__do_sys_sendmmsg net/socket.c:2351 [inline]
__se_sys_sendmmsg net/socket.c:2348 [inline]
__x64_sys_sendmmsg+0x99/0x100 net/socket.c:2348
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fc1b9444ae9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc1b6999188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fc1b9558020 RCX: 00007fc1b9444ae9
RDX: 040000000000009f RSI: 00000000200002c0 RDI: 0000000000000005
RBP: 00007fc1b69991d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000040000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007ffd318b1aaf R14: 00007fc1b6999300 R15: 0000000000022000

Allocated by task 12384:
kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
tcf_block_create net/sched/cls_api.c:505 [inline]
tcf_block_get_ext+0x26a/0x13b0 net/sched/cls_api.c:680
tcf_block_get+0xa9/0xf0 net/sched/cls_api.c:742
cake_init+0x2c9/0xb50 net/sched/sch_cake.c:2667
qdisc_create+0x579/0x1130 net/sched/sch_api.c:1156
tc_modify_qdisc+0x50d/0x1a80 net/sched/sch_api.c:1572
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x3b3/0x8e0 net/socket.c:2227
__sys_sendmmsg+0x195/0x470 net/socket.c:2322
__do_sys_sendmmsg net/socket.c:2351 [inline]
__se_sys_sendmmsg net/socket.c:2348 [inline]
__x64_sys_sendmmsg+0x99/0x100 net/socket.c:2348
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 12384:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
tcf_block_put_ext.part.0+0x5a1/0x6e0 net/sched/cls_api.c:784
tcf_block_put_ext net/sched/cls_api.c:754 [inline]
tcf_block_put+0xad/0x100 net/sched/cls_api.c:797
cake_destroy net/sched/sch_cake.c:2634 [inline]
cake_init+0xa9a/0xb50 net/sched/sch_cake.c:2710
qdisc_create+0x579/0x1130 net/sched/sch_api.c:1156
tc_modify_qdisc+0x50d/0x1a80 net/sched/sch_api.c:1572
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x3b3/0x8e0 net/socket.c:2227
__sys_sendmmsg+0x195/0x470 net/socket.c:2322
__do_sys_sendmmsg net/socket.c:2351 [inline]
__se_sys_sendmmsg net/socket.c:2348 [inline]
__x64_sys_sendmmsg+0x99/0x100 net/socket.c:2348
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 ffff888054ea8480
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 32 bytes inside of
128-byte region [ffff888054ea8480, ffff888054ea8500)
The buggy address belongs to the page:
page:ffffea000153aa00 count:1 mapcount:0 mapping:ffff88813bff0640 index:0xffff888054ea8c00
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea00008d1748 ffffea0000a604c8 ffff88813bff0640
raw: ffff888054ea8c00 ffff888054ea8000 000000010000000e 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888054ea8380: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
ffff888054ea8400: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff888054ea8480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888054ea8500: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff888054ea8580: 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.