general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 PID: 9736 Comm: syz.1.1459 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026 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+0xc80/0x1610 net/sched/sch_fq_codel.c:230 Code: 24 24 48 8b 44 24 20 80 3c 10 00 74 12 4c 89 ef e8 e5 f7 a8 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 c2 f7 a8 f9 48 ba 00 00 00 00 00 fc RSP: 0018:ffffc90002f3f420 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff920005e7ed4 RCX: 1ffff11004bb465a RDX: dffffc0000000000 RSI: 00000000000009ef RDI: 00000000000009f0 RBP: ffffc90002f3f570 R08: ffffffff901e91ef R09: 1ffffffff203d23d R10: dffffc0000000000 R11: fffffbfff203d23e R12: 0000000000000000 R13: ffff88807b3fe000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007fea4f9d26c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000000f000 CR3: 0000000058550000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: qdisc_enqueue include/net/sch_generic.h:842 [inline] netem_dequeue+0xd4c/0x1410 net/sched/sch_netem.c:737 dequeue_skb net/sched/sch_generic.c:295 [inline] qdisc_restart net/sched/sch_generic.c:400 [inline] __qdisc_run+0x22f/0x14b0 net/sched/sch_generic.c:418 __dev_xmit_skb net/core/dev.c:3955 [inline] __dev_queue_xmit+0xdce/0x2e50 net/core/dev.c:4266 packet_snd net/packet/af_packet.c:3094 [inline] packet_sendmsg+0x3cf9/0x50b0 net/packet/af_packet.c:3125 sock_sendmsg_nosec net/socket.c:706 [inline] __sock_sendmsg net/socket.c:718 [inline] __sys_sendto+0x46d/0x620 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: 0033:0x7fea51779e59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fea4f9d2028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007fea51a01fa0 RCX: 00007fea51779e59 RDX: 000000000000fe1d RSI: 00002000000000c0 RDI: 0000000000000005 RBP: 00007fea5180fe6f R08: 0000200000000140 R09: 0000000000000014 R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fea51a02038 R14: 00007fea51a01fa0 R15: 00007ffc9a203ea8 Modules linked in: ---[ end trace 581cf78595fd500b ]--- 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+0xc80/0x1610 net/sched/sch_fq_codel.c:230 Code: 24 24 48 8b 44 24 20 80 3c 10 00 74 12 4c 89 ef e8 e5 f7 a8 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 c2 f7 a8 f9 48 ba 00 00 00 00 00 fc RSP: 0018:ffffc90002f3f420 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff920005e7ed4 RCX: 1ffff11004bb465a RDX: dffffc0000000000 RSI: 00000000000009ef RDI: 00000000000009f0 RBP: ffffc90002f3f570 R08: ffffffff901e91ef R09: 1ffffffff203d23d R10: dffffc0000000000 R11: fffffbfff203d23e R12: 0000000000000000 R13: ffff88807b3fe000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007fea4f9d26c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000000f000 CR3: 0000000058550000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 24 24 and $0x24,%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 e5 f7 a8 f9 call 0xf9a8f7fa 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 c2 f7 a8 f9 call 0xf9a8f7fa 38: 48 rex.W 39: ba 00 00 00 00 mov $0x0,%edx 3e: 00 fc add %bh,%ah