bisecting fixing commit since 1fc596a56b334f4d593a2b49e5ff55af6aaa0816 building syzkaller on be531bb42381b245eed805e49fd889d1c2118c76 testing commit 1fc596a56b334f4d593a2b49e5ff55af6aaa0816 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 3f658c5320e94aef71ad0cf42a096be04c4314e58dbaad0f715cce8c9318035c all runs: crashed: general protection fault in fq_codel_enqueue testing current HEAD 089866061428ec9bf67221247c936792078c41a4 testing commit 089866061428ec9bf67221247c936792078c41a4 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: 3bf69abdc023a375baae63e0539d9af05297995f3770e466509f64faa7d9eab4 all runs: crashed: general protection fault in fq_codel_enqueue revisions tested: 2, total time: 20m9.042924467s (build: 13m13.891443411s, test: 6m5.074483066s) the crash still happens on HEAD commit msg: Merge tag 'libnvdimm-fixes-5.19-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm crash: general protection fault in fq_codel_enqueue 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: 4129 Comm: syz-executor.0 Not tainted 5.19.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 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+0x6ec/0x1030 net/sched/sch_fq_codel.c:230 Code: f9 49 89 d2 49 c1 ea 03 4d 01 fa eb 09 44 39 e5 0f 86 ab 00 00 00 41 80 3a 00 0f 85 5c 06 00 00 48 8b 1a 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 0f 85 02 06 00 00 48 8b 03 48 8d 7b 28 48 89 02 48 RSP: 0018:ffffc90002e272f0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888070480000 RSI: 0000000000000000 RDI: ffff888076374ae8 RBP: 0000000000000040 R08: 0000000000000000 R09: fffff520005c4e9a R10: ffffed100e090000 R11: 0000000000000001 R12: 0000000000000000 R13: ffffc90002e274d0 R14: 0000000000000000 R15: dffffc0000000000 FS: 00007f2dd998b700(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f244d4e4dff CR3: 000000007f9c9000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: dev_qdisc_enqueue+0x39/0x220 net/core/dev.c:3785 __dev_xmit_skb net/core/dev.c:3874 [inline] __dev_queue_xmit+0x1947/0x2ee0 net/core/dev.c:4221 dev_queue_xmit include/linux/netdevice.h:2994 [inline] __bpf_tx_skb net/core/filter.c:2114 [inline] __bpf_redirect_no_mac net/core/filter.c:2139 [inline] __bpf_redirect+0x6e2/0xd30 net/core/filter.c:2162 ____bpf_clone_redirect net/core/filter.c:2429 [inline] bpf_clone_redirect+0x26b/0x3f0 net/core/filter.c:2401 ___bpf_prog_run+0x2fd0/0x74f0 kernel/bpf/core.c:1850 __bpf_prog_run512+0x80/0xc0 kernel/bpf/core.c:2075 bpf_dispatcher_nop_func include/linux/bpf.h:869 [inline] __bpf_prog_run include/linux/filter.h:628 [inline] bpf_prog_run include/linux/filter.h:635 [inline] bpf_test_run+0x3f5/0x890 net/bpf/test_run.c:402 bpf_prog_test_run_skb+0xa01/0x1cb0 net/bpf/test_run.c:1155 bpf_prog_test_run kernel/bpf/syscall.c:3591 [inline] __sys_bpf+0xebe/0x4270 kernel/bpf/syscall.c:4935 __do_sys_bpf kernel/bpf/syscall.c:5021 [inline] __se_sys_bpf kernel/bpf/syscall.c:5019 [inline] __x64_sys_bpf+0x70/0xb0 kernel/bpf/syscall.c:5019 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f2dd8888a39 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2dd998b188 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f2dd899bf60 RCX: 00007f2dd8888a39 RDX: 0000000000000048 RSI: 0000000020000140 RDI: 000000000000000a RBP: 00007f2dd88e2e8f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff1843d2ff R14: 00007f2dd998b300 R15: 0000000000022000 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+0x6ec/0x1030 net/sched/sch_fq_codel.c:230 Code: f9 49 89 d2 49 c1 ea 03 4d 01 fa eb 09 44 39 e5 0f 86 ab 00 00 00 41 80 3a 00 0f 85 5c 06 00 00 48 8b 1a 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 0f 85 02 06 00 00 48 8b 03 48 8d 7b 28 48 89 02 48 RSP: 0018:ffffc90002e272f0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888070480000 RSI: 0000000000000000 RDI: ffff888076374ae8 RBP: 0000000000000040 R08: 0000000000000000 R09: fffff520005c4e9a R10: ffffed100e090000 R11: 0000000000000001 R12: 0000000000000000 R13: ffffc90002e274d0 R14: 0000000000000000 R15: dffffc0000000000 FS: 00007f2dd998b700(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f244d4e4dff CR3: 000000007f9c9000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: f9 stc 1: 49 89 d2 mov %rdx,%r10 4: 49 c1 ea 03 shr $0x3,%r10 8: 4d 01 fa add %r15,%r10 b: eb 09 jmp 0x16 d: 44 39 e5 cmp %r12d,%ebp 10: 0f 86 ab 00 00 00 jbe 0xc1 16: 41 80 3a 00 cmpb $0x0,(%r10) 1a: 0f 85 5c 06 00 00 jne 0x67c 20: 48 8b 1a mov (%rdx),%rbx 23: 48 89 d8 mov %rbx,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1) <-- trapping instruction 2f: 0f 85 02 06 00 00 jne 0x637 35: 48 8b 03 mov (%rbx),%rax 38: 48 8d 7b 28 lea 0x28(%rbx),%rdi 3c: 48 89 02 mov %rax,(%rdx) 3f: 48 rex.W