syzbot


KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler (3)

Status: upstream: reported on 2026/04/28 12:29
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+9bb2ff2a4ab9e17307e1@syzkaller.appspotmail.com
First crash: 1d07h, last: 1d07h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
4bb3719e-3eea-4cc7-bcfb-b0c086c990b2 assessment-kcsan Benign: ❌  Confident: ✅  KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler (3) 2026/04/28 00:55 2026/04/28 00:55 2026/04/28 01:16 8db0407b278f14b1d8bf4df8c9680b9db04f1a59
Discussions (2)
Title Replies (including bot) Last reply
[PATCH net] bonding: 3ad: implement proper RCU rules for port->aggregator 1 (1) 2026/04/28 12:32
[syzbot] [net?] KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler (3) 0 (1) 2026/04/28 12:29
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler (2) net 6 1 969d 966d 0/29 auto-obsoleted due to no activity on 2023/10/31 13:09
upstream KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler net 6 1 1918d 1918d 0/29 auto-closed as invalid on 2021/03/02 22:58

Sample crash report:
8021q: adding VLAN 0 to HW filter on device bond11
==================================================================
BUG: KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler

write to 0xffff88813cf5c4b0 of 8 bytes by task 36 on cpu 0:
 ad_port_selection_logic drivers/net/bonding/bond_3ad.c:1659 [inline]
 bond_3ad_state_machine_handler+0x9d5/0x2d60 drivers/net/bonding/bond_3ad.c:2569
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3385
 worker_thread+0x58a/0x780 kernel/workqueue.c:3466
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88813cf5c4b0 of 8 bytes by task 22063 on cpu 1:
 __bond_3ad_get_active_agg_info drivers/net/bonding/bond_3ad.c:2858 [inline]
 bond_3ad_get_active_agg_info+0x8c/0x230 drivers/net/bonding/bond_3ad.c:2881
 bond_fill_info+0xe0f/0x10f0 drivers/net/bonding/bond_netlink.c:853
 rtnl_link_info_fill net/core/rtnetlink.c:906 [inline]
 rtnl_link_fill+0x1d7/0x4e0 net/core/rtnetlink.c:927
 rtnl_fill_ifinfo+0xf8e/0x1380 net/core/rtnetlink.c:2168
 rtmsg_ifinfo_build_skb+0x11c/0x1b0 net/core/rtnetlink.c:4453
 rtmsg_ifinfo_event net/core/rtnetlink.c:4486 [inline]
 rtmsg_ifinfo+0x6d/0x110 net/core/rtnetlink.c:4495
 __dev_notify_flags+0x76/0x390 net/core/dev.c:9790
 netif_change_flags+0xac/0xd0 net/core/dev.c:9823
 do_setlink+0x905/0x2950 net/core/rtnetlink.c:3180
 rtnl_group_changelink net/core/rtnetlink.c:3813 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3981 [inline]
 rtnl_newlink+0xf55/0x1400 net/core/rtnetlink.c:4109
 rtnetlink_rcv_msg+0x64b/0x720 net/core/rtnetlink.c:6995
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:7022
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5a8/0x680 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x5c8/0x6f0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x563/0x5b0 net/socket.c:2698
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2752
 __sys_sendmsg net/socket.c:2784 [inline]
 __do_sys_sendmsg net/socket.c:2789 [inline]
 __se_sys_sendmsg net/socket.c:2787 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2787
 x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88813cf5c400

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 22063 Comm: syz.0.31122 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================
8021q: adding VLAN 0 to HW filter on device bond12
8021q: adding VLAN 0 to HW filter on device bond13
8021q: adding VLAN 0 to HW filter on device bond14
bridge0: port 1(batadv1) entered blocking state
bridge0: port 1(batadv1) entered listening state
8021q: adding VLAN 0 to HW filter on device batadv1
8021q: adding VLAN 0 to HW filter on device eth0
8021q: adding VLAN 0 to HW filter on device eth1
8021q: adding VLAN 0 to HW filter on device eth2
8021q: adding VLAN 0 to HW filter on device eth3
vlan0: left promiscuous mode
bond15: left promiscuous mode
bridge13: left promiscuous mode
vlan0: left allmulticast mode
bond15: left allmulticast mode
bridge13: left allmulticast mode
ipip0: left promiscuous mode
8021q: adding VLAN 0 to HW filter on device bond16
8021q: adding VLAN 0 to HW filter on device bond0

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/28 00:55 upstream 3b3bea6d4b9c ce741359 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in bond_3ad_get_active_agg_info / bond_3ad_state_machine_handler
* Struck through repros no longer work on HEAD.