device syzkaller0 entered promiscuous mode ============================= WARNING: suspicious RCU usage syzkaller #0 Not tainted ----------------------------- net/sched/sch_api.c:304 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 4 locks held by syz.5.465/6124: #0: ffffffff8c11c7c0 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:313 #1: ffff8880753ac108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:364 [inline] #1: ffff8880753ac108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3911 [inline] #1: ffff8880753ac108 (&sch->q.lock){+.-.}-{2:2}, at: __dev_queue_xmit+0xb8a/0x2ed0 net/core/dev.c:4253 #2: ffff8880753ac148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: packet_snd net/packet/af_packet.c:3089 [inline] #2: ffff8880753ac148 (dev->qdisc_running_key ?: &qdisc_running_key){+...}-{0:0}, at: packet_sendmsg+0x3d52/0x4fe0 net/packet/af_packet.c:3120 #3: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:312 stack backtrace: CPU: 0 PID: 6124 Comm: syz.5.465 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 qdisc_lookup+0xa6/0x650 net/sched/sch_api.c:304 qdisc_tree_reduce_backlog+0x190/0x430 net/sched/sch_api.c:793 cake_drop net/sched/sch_cake.c:1611 [inline] cake_enqueue+0x3889/0x7bb0 net/sched/sch_cake.c:1948 qdisc_enqueue include/net/sch_generic.h:832 [inline] netem_dequeue+0xd39/0x1400 net/sched/sch_netem.c:737 dequeue_skb net/sched/sch_generic.c:292 [inline] qdisc_restart net/sched/sch_generic.c:397 [inline] __qdisc_run+0x237/0x1480 net/sched/sch_generic.c:415 __dev_xmit_skb net/core/dev.c:3942 [inline] __dev_queue_xmit+0xeb9/0x2ed0 net/core/dev.c:4253 packet_snd net/packet/af_packet.c:3089 [inline] packet_sendmsg+0x3d52/0x4fe0 net/packet/af_packet.c:3120 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] __sys_sendto+0x423/0x580 net/socket.c:2073 __do_sys_sendto net/socket.c:2085 [inline] __se_sys_sendto net/socket.c:2081 [inline] __x64_sys_sendto+0xda/0xf0 net/socket.c:2081 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 RIP: 0033:0x7f1755a8c6c9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f1753cf3038 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f1755ce2fa0 RCX: 00007f1755a8c6c9 RDX: 000000000000000e RSI: 00002000000005c0 RDI: 0000000000000007 RBP: 00007f1755b0ef91 R08: 00002000000001c0 R09: 0000000000000014 R10: 0000000000000040 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1755ce3038 R14: 00007f1755ce2fa0 R15: 00007fff34bd0b28