On Mon, May 04 2026 at 05:23, syzbot wrote: Cc'ed network/bridge people as that's clearly in their realm.
> Hello, > > syzbot found the following issue on: > > HEAD commit: 6d35786de281 Merge tag 'for-linus' of git://git.kernel.org.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=126bf21f980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=f2e8ebfec4636d32 > dashboard link: https://syzkaller.appspot.com/bug?extid=ae231e0552fa77b26ea1 > compiler: Debian clang version 21.1.8 > (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: > https://storage.googleapis.com/syzbot-assets/b3ab34c4c807/disk-6d35786d.raw.xz > vmlinux: > https://storage.googleapis.com/syzbot-assets/03f465478178/vmlinux-6d35786d.xz > kernel image: > https://storage.googleapis.com/syzbot-assets/29d261604425/bzImage-6d35786d.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: [email protected] > > ------------[ cut here ]------------ > ODEBUG: free active (active state 0) object: ffff888033a47278 object type: > timer_list hint: br_ip6_multicast_port_query_expired+0x0/0x380 > net/bridge/br_multicast.c:-1 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ An object which contains an active timer is RCU freed.... > WARNING: lib/debugobjects.c:632 at debug_print_object lib/debugobjects.c:629 > [inline], CPU#1: rcuc/1/28 > WARNING: lib/debugobjects.c:632 at __debug_check_no_obj_freed > lib/debugobjects.c:1116 [inline], CPU#1: rcuc/1/28 > WARNING: lib/debugobjects.c:632 at debug_check_no_obj_freed+0x405/0x550 > lib/debugobjects.c:1146, CPU#1: rcuc/1/28 > Modules linked in: > CPU: 1 UID: 0 PID: 28 Comm: rcuc/1 Tainted: G L syzkaller #0 > PREEMPT_{RT,(full)} > Tainted: [L]=SOFTLOCKUP > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 04/18/2026 > RIP: 0010:debug_print_object lib/debugobjects.c:629 [inline] > RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:1116 [inline] > RIP: 0010:debug_check_no_obj_freed+0x44a/0x550 lib/debugobjects.c:1146 > Code: 89 44 24 20 e8 27 81 7f fd 48 8b 44 24 20 4c 8b 4d 00 4c 89 ef 48 c7 c6 > a0 53 a7 8b 48 c7 c2 20 59 a7 8b 8b 0c 24 4d 89 f8 50 <67> 48 0f b9 3a 48 83 > c4 08 4c 8b 6c 24 18 48 b9 00 00 00 00 00 fc > RSP: 0018:ffffc90000a2fa90 EFLAGS: 00010246 > RAX: ffffffff89f32240 RBX: ffffffff99a8edc0 RCX: 0000000000000000 > RDX: ffffffff8ba75920 RSI: ffffffff8ba753a0 RDI: ffffffff8f933740 > RBP: ffffffff8b4f5380 R08: ffff888033a47278 R09: ffffffff8b4f6700 > R10: dffffc0000000000 R11: ffffffff81b0c180 R12: ffff888033a47400 > R13: ffffffff8f933740 R14: ffff888033a47000 R15: ffff888033a47278 > FS: 0000000000000000(0000) GS:ffff888126279000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fb873a4da08 CR3: 000000004cc78000 CR4: 00000000003526f0 > Call Trace: > <TASK> > slab_free_hook mm/slub.c:2620 [inline] > slab_free mm/slub.c:6250 [inline] > kfree+0x13e/0x6c0 mm/slub.c:6565 > kobject_cleanup lib/kobject.c:689 [inline] > kobject_release lib/kobject.c:720 [inline] > kref_put include/linux/kref.h:65 [inline] > kobject_put+0x228/0x560 lib/kobject.c:737 > rcu_do_batch kernel/rcu/tree.c:2617 [inline] > rcu_core kernel/rcu/tree.c:2869 [inline] > rcu_cpu_kthread+0x99e/0x1470 kernel/rcu/tree.c:2957 > smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160 > kthread+0x388/0x470 kernel/kthread.c:436 > ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > </TASK>
