Re: [syzbot] WARNING: ODEBUG bug in route4_destroy

From: syzbot
Date: Thu Jun 16 2022 - 08:26:13 EST

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Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in route4_destroy

==================================================================
BUG: KASAN: use-after-free in route4_destroy+0x852/0xa10 net/sched/cls_route.c:305
Read of size 8 at addr ffff88801fcbe000 by task syz-executor.0/4164

CPU: 1 PID: 4164 Comm: syz-executor.0 Not tainted 5.19.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xeb/0x495 mm/kasan/report.c:313
print_report mm/kasan/report.c:429 [inline]
kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
route4_destroy+0x852/0xa10 net/sched/cls_route.c:305
tcf_proto_destroy+0x6a/0x2d0 net/sched/cls_api.c:314
tcf_proto_put+0x8c/0xc0 net/sched/cls_api.c:326
tcf_chain_flush+0x21a/0x360 net/sched/cls_api.c:632
tcf_block_flush_all_chains net/sched/cls_api.c:1034 [inline]
__tcf_block_put+0x15a/0x510 net/sched/cls_api.c:1196
tcf_block_put_ext net/sched/cls_api.c:1396 [inline]
tcf_block_put+0xb3/0x100 net/sched/cls_api.c:1411
drr_destroy_qdisc+0x44/0x1d0 net/sched/sch_drr.c:455
qdisc_destroy+0xc4/0x4e0 net/sched/sch_generic.c:1067
qdisc_put+0xcd/0xe0 net/sched/sch_generic.c:1086
notify_and_destroy net/sched/sch_api.c:1012 [inline]
qdisc_graft+0xeb1/0x1270 net/sched/sch_api.c:1084
tc_modify_qdisc+0xbb7/0x1a00 net/sched/sch_api.c:1671
rtnetlink_rcv_msg+0x43a/0xc90 net/core/rtnetlink.c:6089
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
____sys_sendmsg+0x6eb/0x810 net/socket.c:2492
___sys_sendmsg+0xf3/0x170 net/socket.c:2546
__sys_sendmsg net/socket.c:2575 [inline]
__do_sys_sendmsg net/socket.c:2584 [inline]
__se_sys_sendmsg net/socket.c:2582 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2582
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x4665f9
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:00007fd7310da188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665f9
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffc67b9e05f R14: 00007fd7310da300 R15: 0000000000022000
</TASK>

Allocated by task 4160:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
____kasan_kmalloc mm/kasan/common.c:515 [inline]
____kasan_kmalloc mm/kasan/common.c:474 [inline]
__kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:524
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:733 [inline]
route4_change+0x28c/0x2450 net/sched/cls_route.c:505
tc_new_tfilter+0x98d/0x2200 net/sched/cls_api.c:2148
rtnetlink_rcv_msg+0x946/0xc90 net/core/rtnetlink.c:6080
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
____sys_sendmsg+0x6eb/0x810 net/socket.c:2492
___sys_sendmsg+0xf3/0x170 net/socket.c:2546
__sys_sendmsg net/socket.c:2575 [inline]
__do_sys_sendmsg net/socket.c:2584 [inline]
__se_sys_sendmsg net/socket.c:2582 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2582
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0

Freed by task 1095:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0x166/0x1a0 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
slab_free_hook mm/slub.c:1727 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1753
slab_free mm/slub.c:3507 [inline]
kfree+0xd6/0x4d0 mm/slub.c:4555
__route4_delete_filter net/sched/cls_route.c:262 [inline]
route4_delete_filter_work+0xb0/0xf0 net/sched/cls_route.c:271
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302

Last potentially related work creation:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
__kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
insert_work+0x48/0x350 kernel/workqueue.c:1358
__queue_work+0x62f/0x1150 kernel/workqueue.c:1517
rcu_work_rcufn+0x58/0x80 kernel/workqueue.c:1754
rcu_do_batch kernel/rcu/tree.c:2578 [inline]
rcu_core+0x7b1/0x1880 kernel/rcu/tree.c:2838
__do_softirq+0x29b/0x9c2 kernel/softirq.c:571

Second to last potentially related work creation:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
__kasan_record_aux_stack+0xbe/0xd0 mm/kasan/generic.c:348
call_rcu+0x99/0x790 kernel/rcu/tree.c:3126
queue_rcu_work+0x82/0xa0 kernel/workqueue.c:1774
route4_queue_work+0x46/0x50 net/sched/cls_route.c:279
route4_change+0x1a73/0x2450 net/sched/cls_route.c:564
tc_new_tfilter+0x98d/0x2200 net/sched/cls_api.c:2148
rtnetlink_rcv_msg+0x946/0xc90 net/core/rtnetlink.c:6080
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:734
____sys_sendmsg+0x6eb/0x810 net/socket.c:2492
___sys_sendmsg+0xf3/0x170 net/socket.c:2546
__sys_sendmsg net/socket.c:2575 [inline]
__do_sys_sendmsg net/socket.c:2584 [inline]
__se_sys_sendmsg net/socket.c:2582 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2582
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x46/0xb0

The buggy address belongs to the object at ffff88801fcbe000
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 0 bytes inside of
192-byte region [ffff88801fcbe000, ffff88801fcbe0c0)

The buggy address belongs to the physical page:
page:ffffea00007f2f80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1fcbe
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00007d50c0 dead000000000002 ffff888010c41a00
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12c00(GFP_NOIO|__GFP_NOWARN|__GFP_NORETRY), pid 146, tgid 146 (kworker/0:2), ts 9150330232, free_ts 9143712005
prep_new_page mm/page_alloc.c:2456 [inline]
get_page_from_freelist+0x1290/0x3b70 mm/page_alloc.c:4198
__alloc_pages+0x1c7/0x510 mm/page_alloc.c:5426
alloc_pages+0x1aa/0x310 mm/mempolicy.c:2272
alloc_slab_page mm/slub.c:1797 [inline]
allocate_slab+0x26c/0x3c0 mm/slub.c:1942
new_slab mm/slub.c:2002 [inline]
___slab_alloc+0x985/0xd90 mm/slub.c:3002
__slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3089
slab_alloc_node mm/slub.c:3180 [inline]
slab_alloc mm/slub.c:3222 [inline]
__kmalloc+0x318/0x350 mm/slub.c:4413
kmalloc include/linux/slab.h:605 [inline]
usb_alloc_urb+0xa5/0xb0 drivers/usb/core/urb.c:74
usb_internal_control_msg drivers/usb/core/message.c:95 [inline]
usb_control_msg+0x1c9/0x4a0 drivers/usb/core/message.c:153
get_port_status drivers/usb/core/hub.c:580 [inline]
hub_ext_port_status+0x112/0x450 drivers/usb/core/hub.c:597
hub_port_status drivers/usb/core/hub.c:619 [inline]
hub_activate+0xa5c/0x1c90 drivers/usb/core/hub.c:1129
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1371 [inline]
free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1421
free_unref_page_prepare mm/page_alloc.c:3343 [inline]
free_unref_page+0x19/0x6a0 mm/page_alloc.c:3438
mm_free_pgd kernel/fork.c:737 [inline]
__mmdrop+0xcb/0x3f0 kernel/fork.c:788
mmdrop include/linux/sched/mm.h:50 [inline]
__mmput+0x3f1/0x4b0 kernel/fork.c:1197
mmput+0x56/0x60 kernel/fork.c:1208
free_bprm+0x65/0x2e0 fs/exec.c:1486
kernel_execve+0x3fa/0x500 fs/exec.c:2005
call_usermodehelper_exec_async+0x2e3/0x580 kernel/umh.c:112
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302

Memory state around the buggy address:
ffff88801fcbdf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88801fcbdf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801fcbe000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88801fcbe080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88801fcbe100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Tested on:

commit: 018ab4fa netfs: fix up netfs_inode_init() docbook comm..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=13ff8ac3f00000
kernel config: https://syzkaller.appspot.com/x/.config?x=f21890d74080ef72
dashboard link: https://syzkaller.appspot.com/bug?extid=2e3efb5eb71cb5075ba7
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=14a571a7f00000

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