[syzbot] KASAN: use-after-free Read in ovs_vport_locate

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 041fae9c105a Merge tag 'f2fs-for-6.2-rc1' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15c5d020480000
kernel config: https://syzkaller.appspot.com/x/.config?x=836aafbf33f4fa6c
dashboard link: https://syzkaller.appspot.com/bug?extid=8f4e2dcfcb3209ac35f9
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/30e749b24df4/disk-041fae9c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dd6d972f5b02/vmlinux-041fae9c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/405163d7c7cc/bzImage-041fae9c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8f4e2d...@syzkaller.appspotmail.com

netlink: 208 bytes leftover after parsing attributes in process `syz-executor.4'.
==================================================================
BUG: KASAN: use-after-free in read_pnet include/net/net_namespace.h:383 [inline]
BUG: KASAN: use-after-free in ovs_dp_get_net net/openvswitch/datapath.h:195 [inline]
BUG: KASAN: use-after-free in ovs_vport_locate+0x131/0x150 net/openvswitch/vport.c:103
Read of size 8 at addr ffff88802055e360 by task syz-executor.4/5621

CPU: 0 PID: 5621 Comm: syz-executor.4 Not tainted 6.1.0-syzkaller-10971-g041fae9c105a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:306 [inline]
print_report+0x15e/0x461 mm/kasan/report.c:417
kasan_report+0xbf/0x1f0 mm/kasan/report.c:517
read_pnet include/net/net_namespace.h:383 [inline]
ovs_dp_get_net net/openvswitch/datapath.h:195 [inline]
ovs_vport_locate+0x131/0x150 net/openvswitch/vport.c:103
lookup_datapath+0x54/0x3a0 net/openvswitch/datapath.c:1628
ovs_dp_reset_user_features net/openvswitch/datapath.c:1639 [inline]
ovs_dp_cmd_new+0xd5b/0x11c0 net/openvswitch/datapath.c:1848
genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968
genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065
netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xd3/0x120 net/socket.c:734
____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
__sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f142348c0d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f14240ff168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f14235abf80 RCX: 00007f142348c0d9
RDX: 0000000000000800 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 00007f14234e7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdd965a34f R14: 00007f14240ff300 R15: 0000000000022000
</TASK>

Allocated by task 5564:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:371 [inline]
____kasan_kmalloc mm/kasan/common.c:330 [inline]
__kasan_kmalloc+0xa3/0xb0 mm/kasan/common.c:380
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
ovs_dp_cmd_new+0x1a3/0x11c0 net/openvswitch/datapath.c:1796
genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968
genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065
netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xd3/0x120 net/socket.c:734
____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
__sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5564:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:518
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x13b/0x1a0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:177 [inline]
__cache_free mm/slab.c:3394 [inline]
__do_kmem_cache_free mm/slab.c:3580 [inline]
__kmem_cache_free+0xcd/0x3b0 mm/slab.c:3587
ovs_dp_cmd_new+0x25e/0x11c0 net/openvswitch/datapath.c:1884
genl_family_rcv_msg_doit.isra.0+0x1e6/0x2d0 net/netlink/genetlink.c:968
genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline]
genl_rcv_msg+0x4ff/0x7e0 net/netlink/genetlink.c:1065
netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1076
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xd3/0x120 net/socket.c:734
____sys_sendmsg+0x712/0x8c0 net/socket.c:2476
___sys_sendmsg+0x110/0x1b0 net/socket.c:2530
__sys_sendmsg+0xf7/0x1c0 net/socket.c:2559
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Last potentially related work creation:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
__kasan_record_aux_stack+0x7b/0x90 mm/kasan/generic.c:488
insert_work+0x48/0x350 kernel/workqueue.c:1358
__queue_work+0x693/0x13b0 kernel/workqueue.c:1517
queue_work_on+0xf2/0x110 kernel/workqueue.c:1545
queue_work include/linux/workqueue.h:503 [inline]
addr_event.part.0+0x33e/0x4f0 drivers/infiniband/core/roce_gid_mgmt.c:853
addr_event drivers/infiniband/core/roce_gid_mgmt.c:824 [inline]
inet6addr_event+0x142/0x1c0 drivers/infiniband/core/roce_gid_mgmt.c:883
notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
atomic_notifier_call_chain+0x74/0x180 kernel/notifier.c:225
ipv6_add_addr+0x1266/0x1de0 net/ipv6/addrconf.c:1165
addrconf_add_linklocal+0x1cc/0x590 net/ipv6/addrconf.c:3215
addrconf_addr_gen+0x326/0x370 net/ipv6/addrconf.c:3346
addrconf_dev_config+0x255/0x410 net/ipv6/addrconf.c:3391
addrconf_notify+0xfb6/0x1c80 net/ipv6/addrconf.c:3635
notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1944
netdev_state_change net/core/dev.c:1319 [inline]
netdev_state_change+0x104/0x130 net/core/dev.c:1312
linkwatch_do_dev+0x10e/0x150 net/core/link_watch.c:182
__linkwatch_run_queue+0x23f/0x6a0 net/core/link_watch.c:235
linkwatch_event+0x4e/0x70 net/core/link_watch.c:278
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x669/0x1090 kernel/workqueue.c:2436
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

Second to last potentially related work creation:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
__kasan_record_aux_stack+0x7b/0x90 mm/kasan/generic.c:488
insert_work+0x48/0x350 kernel/workqueue.c:1358
__queue_work+0x693/0x13b0 kernel/workqueue.c:1517
queue_work_on+0xf2/0x110 kernel/workqueue.c:1545
queue_work include/linux/workqueue.h:503 [inline]
netdevice_queue_work drivers/infiniband/core/roce_gid_mgmt.c:659 [inline]
netdevice_event+0x5e9/0x8f0 drivers/infiniband/core/roce_gid_mgmt.c:802
notifier_call_chain+0xb5/0x200 kernel/notifier.c:87
call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:1944
call_netdevice_notifiers_extack net/core/dev.c:1982 [inline]
call_netdevice_notifiers net/core/dev.c:1996 [inline]
register_netdevice+0xfb4/0x1640 net/core/dev.c:10078
bond_newlink drivers/net/bonding/bond_netlink.c:560 [inline]
bond_newlink+0x4b/0xa0 drivers/net/bonding/bond_netlink.c:550
rtnl_newlink_create net/core/rtnetlink.c:3407 [inline]
__rtnl_newlink+0x10c2/0x1840 net/core/rtnetlink.c:3624
rtnl_newlink+0x68/0xa0 net/core/rtnetlink.c:3637
rtnetlink_rcv_msg+0x43e/0xca0 net/core/rtnetlink.c:6141
netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2564
netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1356
netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1932
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg+0xd3/0x120 net/socket.c:734
__sys_sendto+0x23a/0x340 net/socket.c:2117
__do_sys_sendto net/socket.c:2129 [inline]
__se_sys_sendto net/socket.c:2125 [inline]
__x64_sys_sendto+0xe1/0x1b0 net/socket.c:2125
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88802055e300
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 96 bytes inside of
192-byte region [ffff88802055e300, ffff88802055e3c0)

The buggy address belongs to the physical page:
page:ffffea0000815780 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802055ef00 pfn:0x2055e
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffff888012040000 ffffea0000873fd0 ffffea000083f490
raw: ffff88802055ef00 ffff88802055e000 000000010000000e 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 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 1, tgid 1 (swapper/0), ts 8303233753, free_ts 8269599359
prep_new_page mm/page_alloc.c:2531 [inline]
get_page_from_freelist+0x119c/0x2ce0 mm/page_alloc.c:4283
__alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5549
__alloc_pages_node include/linux/gfp.h:237 [inline]
kmem_getpages mm/slab.c:1363 [inline]
cache_grow_begin+0x94/0x390 mm/slab.c:2574
cache_alloc_refill+0x27f/0x380 mm/slab.c:2947
____cache_alloc mm/slab.c:3023 [inline]
____cache_alloc mm/slab.c:3006 [inline]
__do_cache_alloc mm/slab.c:3206 [inline]
slab_alloc_node mm/slab.c:3254 [inline]
__kmem_cache_alloc_node+0x44f/0x510 mm/slab.c:3544
kmalloc_trace+0x26/0x60 mm/slab_common.c:1062
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
call_usermodehelper_setup+0x9c/0x340 kernel/umh.c:366
kobject_uevent_env+0xed3/0x1620 lib/kobject_uevent.c:614
device_add+0xb76/0x1e90 drivers/base/core.c:3498
rfkill_register+0x1a9/0xb00 net/rfkill/core.c:1070
wiphy_register+0x24ae/0x2ae0 net/wireless/core.c:1007
virt_wifi_make_wiphy drivers/net/wireless/virt_wifi.c:383 [inline]
virt_wifi_init_module+0x352/0x3da drivers/net/wireless/virt_wifi.c:665
do_one_initcall+0x141/0x790 init/main.c:1306
do_initcall_level init/main.c:1379 [inline]
do_initcalls init/main.c:1395 [inline]
do_basic_setup init/main.c:1414 [inline]
kernel_init_freeable+0x6f9/0x782 init/main.c:1634
kernel_init+0x1e/0x1d0 init/main.c:1522
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1446 [inline]
free_pcp_prepare+0x65c/0xc00 mm/page_alloc.c:1496
free_unref_page_prepare mm/page_alloc.c:3369 [inline]
free_unref_page+0x1d/0x490 mm/page_alloc.c:3464
__vunmap+0x85d/0xd30 mm/vmalloc.c:2727
free_work+0x5c/0x80 mm/vmalloc.c:100
process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
worker_thread+0x669/0x1090 kernel/workqueue.c:2436
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

Memory state around the buggy address:
ffff88802055e200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88802055e280: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802055e300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802055e380: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88802055e400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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[Paolo Abeni]

@Eelco, @Aaron: could you please have a look? I think the
ovs_dp_cmd_new() error path does not clean correctly the to-be-deleted
datapath, possibly a ovs_dp_detach_port() call for the internal one is
missing.

Thanks,

Paolo

[Aaron Conole]

Okay - I'll have a look. I guess there could be some missing protection
as well during allocation / reference. Either way, building a KASAN
kernel now. Thanks for the report!

> Thanks,
>
> Paolo