general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 PID: 8965 Comm: syz.5.1028 Not tainted 6.1.148-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:dequeue_head net/sched/sch_fq_codel.c:120 [inline] RIP: 0010:fq_codel_drop net/sched/sch_fq_codel.c:168 [inline] RIP: 0010:fq_codel_enqueue+0xd2d/0x1590 net/sched/sch_fq_codel.c:230 Code: 24 08 48 8b 44 24 20 80 3c 10 00 74 12 4c 89 ef e8 e8 92 82 f9 48 ba 00 00 00 00 00 fc ff df 4d 8b 65 00 4c 89 e0 48 c1 e8 03 <80> 3c 10 00 74 12 4c 89 e7 e8 c5 92 82 f9 48 ba 00 00 00 00 00 fc RSP: 0000:ffffc9000c52f460 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff920018a5ee8 RCX: 1ffff11006210d5a RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc9000c52f5b0 R08: dffffc0000000000 R09: fffffbfff215bc82 R10: fffffbfff215bc82 R11: 1ffffffff215bc81 R12: 0000000000000000 R13: ffff8880294b0000 R14: 0000000000000000 R15: 0000000000000000 FS: 00005555909e3500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2ee18ff8 CR3: 0000000073cf1000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: cbs_child_enqueue net/sched/sch_cbs.c:95 [inline] cbs_enqueue_soft+0x1a8/0x270 net/sched/sch_cbs.c:128 dev_qdisc_enqueue+0x4c/0x2b0 net/core/dev.c:3863 __dev_xmit_skb net/core/dev.c:3952 [inline] __dev_queue_xmit+0xf8e/0x3760 net/core/dev.c:4300 dev_queue_xmit include/linux/netdevice.h:3051 [inline] tipc_l2_send_msg+0x30f/0x3d0 net/tipc/bearer.c:518 tipc_bearer_xmit_skb+0x2a9/0x3f0 net/tipc/bearer.c:577 tipc_disc_timeout+0x568/0x6b0 net/tipc/discover.c:338 call_timer_fn+0x1a0/0x670 kernel/time/timer.c:1504 expire_timers kernel/time/timer.c:1549 [inline] __run_timers+0x525/0x7c0 kernel/time/timer.c:1820 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1833 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596 __do_softirq kernel/softirq.c:630 [inline] invoke_softirq kernel/softirq.c:470 [inline] __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:679 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691 RIP: 0033:0x7f8c9ee68004 Code: 0f 82 b9 00 00 00 48 39 f2 72 6e 41 0f 11 0c 24 48 8b 77 f8 48 89 f8 48 89 eb eb 12 66 2e 0f 1f 84 00 00 00 00 00 48 8b 4b 08 <48> 83 c3 08 48 39 d1 72 f3 48 83 e8 08 48 39 f2 73 17 66 2e 0f 1f RSP: 002b:00007ffc445f2d70 EFLAGS: 00000297 RAX: 00007f8c9e99aaa8 RBX: 00007f8c9e99a738 RCX: ffffffff8a06340a RDX: ffffffff8a06340a RSI: ffffffff8a06340a RDI: 00007f8c9e99b870 RBP: 00007f8c9e9993d8 R08: 00007f8c9e99a620 R09: 00007f8c9f1a2000 R10: 00007f8c9e5fd008 R11: 0000000000000008 R12: 00007f8c9e9993d0 R13: 0000000000000018 R14: ffffffffffffffff R15: 00007f8c9e5fd008 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:dequeue_head net/sched/sch_fq_codel.c:120 [inline] RIP: 0010:fq_codel_drop net/sched/sch_fq_codel.c:168 [inline] RIP: 0010:fq_codel_enqueue+0xd2d/0x1590 net/sched/sch_fq_codel.c:230 Code: 24 08 48 8b 44 24 20 80 3c 10 00 74 12 4c 89 ef e8 e8 92 82 f9 48 ba 00 00 00 00 00 fc ff df 4d 8b 65 00 4c 89 e0 48 c1 e8 03 <80> 3c 10 00 74 12 4c 89 e7 e8 c5 92 82 f9 48 ba 00 00 00 00 00 fc RSP: 0000:ffffc9000c52f460 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff920018a5ee8 RCX: 1ffff11006210d5a RDX: dffffc0000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc9000c52f5b0 R08: dffffc0000000000 R09: fffffbfff215bc82 R10: fffffbfff215bc82 R11: 1ffffffff215bc81 R12: 0000000000000000 R13: ffff8880294b0000 R14: 0000000000000000 R15: 0000000000000000 FS: 00005555909e3500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2ee18ff8 CR3: 0000000073cf1000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 24 08 and $0x8,%al 2: 48 8b 44 24 20 mov 0x20(%rsp),%rax 7: 80 3c 10 00 cmpb $0x0,(%rax,%rdx,1) b: 74 12 je 0x1f d: 4c 89 ef mov %r13,%rdi 10: e8 e8 92 82 f9 call 0xf98292fd 15: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx 1c: fc ff df 1f: 4d 8b 65 00 mov 0x0(%r13),%r12 23: 4c 89 e0 mov %r12,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 80 3c 10 00 cmpb $0x0,(%rax,%rdx,1) <-- trapping instruction 2e: 74 12 je 0x42 30: 4c 89 e7 mov %r12,%rdi 33: e8 c5 92 82 f9 call 0xf98292fd 38: 48 rex.W 39: ba 00 00 00 00 mov $0x0,%edx 3e: 00 fc add %bh,%ah