[moderation] [batman?] KCSAN: data-race in batadv_iv_ogm_schedule / batadv_update_min_mtu (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5723cc3450bc Merge tag 'dmaengine-fix-6.15' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13439f68580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7bf27d52ff5e6b29
dashboard link: https://syzkaller.appspot.com/bug?extid=8bb1e252452be5efb2b2
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
CC: [ant...@mandelbit.com b.a.t...@lists.open-mesh.org da...@davemloft.net edum...@google.com ho...@kernel.org ku...@kernel.org linux-...@vger.kernel.org marek....@mailbox.org net...@vger.kernel.org pab...@redhat.com sv...@narfation.org s...@simonwunderlich.de]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c7b5c300a6b4/disk-5723cc34.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a07e7f9a7f86/vmlinux-5723cc34.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d28a3b5b4b27/bzImage-5723cc34.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8bb1e2...@syzkaller.appspotmail.com

batman_adv: batadv0: Interface activated: batadv_slave_0
==================================================================
BUG: KCSAN: data-race in batadv_iv_ogm_schedule / batadv_update_min_mtu

write to 0xffff88811777f610 of 1 bytes by task 3408 on cpu 1:
batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:811 [inline]
batadv_iv_ogm_schedule+0xab/0x740 net/batman-adv/bat_iv_ogm.c:876
batadv_iv_send_outstanding_bat_ogm_packet+0x419/0x470 net/batman-adv/bat_iv_ogm.c:1720
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
worker_thread+0x582/0x770 kernel/workqueue.c:3400
kthread+0x486/0x510 kernel/kthread.c:464
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811777f610 of 1 bytes by task 3314 on cpu 0:
batadv_hardif_min_mtu net/batman-adv/hard-interface.c:593 [inline]
batadv_update_min_mtu+0x45/0x1a0 net/batman-adv/hard-interface.c:640
batadv_hardif_activate_interface+0x1b3/0x2f0 net/batman-adv/hard-interface.c:680
batadv_hard_if_event+0x3b3/0x1070 net/batman-adv/hard-interface.c:975
notifier_call_chain kernel/notifier.c:85 [inline]
raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453
call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:2176
call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
call_netdevice_notifiers net/core/dev.c:2228 [inline]
__dev_notify_flags+0xff/0x1a0 net/core/dev.c:-1
netif_change_flags+0xac/0xd0 net/core/dev.c:9422
do_setlink+0x90e/0x27f0 net/core/rtnetlink.c:3152
rtnl_changelink net/core/rtnetlink.c:3769 [inline]
__rtnl_newlink net/core/rtnetlink.c:3928 [inline]
rtnl_newlink+0xe75/0x12d0 net/core/rtnetlink.c:4065
rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6955
netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2534
rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6982
netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
netlink_unicast+0x5a1/0x670 net/netlink/af_netlink.c:1339
netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1883
sock_sendmsg_nosec net/socket.c:712 [inline]
__sock_sendmsg+0x145/0x180 net/socket.c:727
__sys_sendto+0x268/0x330 net/socket.c:2180
__do_sys_sendto net/socket.c:2187 [inline]
__se_sys_sendto net/socket.c:2183 [inline]
__x64_sys_sendto+0x76/0x90 net/socket.c:2183
x64_sys_call+0x2eb6/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:45
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x04 -> 0x03

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3314 Comm: syz-executor Not tainted 6.15.0-rc6-syzkaller-00346-g5723cc3450bc #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
==================================================================
batman_adv: batadv0: Interface activated: batadv_slave_1
netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.