[moderation] [batman?] KCSAN: data-race in batadv_tt_local_add / batadv_tt_local_commit_changes_nolock (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3e48a11675c5 Merge tag 'f2fs-for-7.0-rc1' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1033c15a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a6d4a8c8877f1220
dashboard link: https://syzkaller.appspot.com/bug?extid=50a602f0e0b3e0394501
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
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/d3148718ad7b/disk-3e48a116.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e7bdcd969168/vmlinux-3e48a116.xz
kernel image: https://storage.googleapis.com/syzbot-assets/09feb54a2727/bzImage-3e48a116.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+50a602...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in batadv_tt_local_add / batadv_tt_local_commit_changes_nolock

read to 0xffff888108109518 of 2 bytes by task 206 on cpu 0:
batadv_tt_local_set_flags net/batman-adv/translation-table.c:3570 [inline]
batadv_tt_local_commit_changes_nolock+0xe2/0x570 net/batman-adv/translation-table.c:3643
batadv_tt_local_commit_changes+0x26/0x40 net/batman-adv/translation-table.c:3667
batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:819 [inline]
batadv_iv_ogm_schedule+0x249/0x810 net/batman-adv/bat_iv_ogm.c:873
batadv_iv_send_outstanding_bat_ogm_packet+0x419/0x470 net/batman-adv/bat_iv_ogm.c:1709
process_one_work kernel/workqueue.c:3275 [inline]
process_scheduled_works+0x4de/0x9e0 kernel/workqueue.c:3358
worker_thread+0x581/0x770 kernel/workqueue.c:3439
kthread+0x22a/0x280 kernel/kthread.c:467
ret_from_fork+0x150/0x360 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read-write to 0xffff888108109518 of 2 bytes by task 4635 on cpu 1:
batadv_tt_local_add+0xdcd/0x1720 net/batman-adv/translation-table.c:-1
batadv_interface_tx+0x42b/0xae0 net/batman-adv/mesh-interface.c:236
__netdev_start_xmit include/linux/netdevice.h:5275 [inline]
netdev_start_xmit include/linux/netdevice.h:5284 [inline]
xmit_one net/core/dev.c:3864 [inline]
dev_hard_start_xmit+0x136/0x3f0 net/core/dev.c:3880
__dev_queue_xmit+0xd9c/0x1f40 net/core/dev.c:4829
dev_queue_xmit include/linux/netdevice.h:3384 [inline]
__bpf_tx_skb net/core/filter.c:2153 [inline]
__bpf_redirect_common net/core/filter.c:2197 [inline]
__bpf_redirect+0x862/0x990 net/core/filter.c:2204
____bpf_clone_redirect net/core/filter.c:2487 [inline]
bpf_clone_redirect+0x20c/0x290 net/core/filter.c:2450
bpf_prog_ba7156dd260b21a3+0x62/0x6b
bpf_dispatcher_nop_func include/linux/bpf.h:1402 [inline]
__bpf_prog_run include/linux/filter.h:723 [inline]
bpf_prog_run include/linux/filter.h:730 [inline]
bpf_test_run+0x29d/0x620 net/bpf/test_run.c:423
bpf_prog_test_run_skb+0x9a4/0xef0 net/bpf/test_run.c:1159
bpf_prog_test_run+0x204/0x340 kernel/bpf/syscall.c:4722
__sys_bpf+0x52e/0x7e0 kernel/bpf/syscall.c:6247
__do_sys_bpf kernel/bpf/syscall.c:6342 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6340 [inline]
__x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6340
x64_sys_call+0x10cb/0x3020 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0200 -> 0x0000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 4635 Comm: syz.4.415 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================


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