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: 0617557cd0036b56cee34204bcae72d11fd2544c3cb22272d7c9d0f9d6b01dbf all runs: crashed: general protection fault in fq_codel_enqueue testing current HEAD 3123109284176b1532874591f7c81f3837bbdc17 testing commit 3123109284176b1532874591f7c81f3837bbdc17 compiler: gcc (GCC) 10.2.1 20210217, GNU ld (GNU Binutils for Debian) 2.35.2 kernel signature: c78bc5c8521af194e1edf2eef2cbf3dbf7d196b17b8e0c0b744cf11d4808a90c all runs: crashed: general protection fault in fq_codel_enqueue revisions tested: 2, total time: 18m42.082311091s (build: 12m6.720438348s, test: 5m48.846218685s) the crash still happens on HEAD commit msg: Linux 5.18-rc1 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: 4079 Comm: syz-executor.0 Not tainted 5.18.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 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:ffffc900033d72f0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888070700000 RSI: 0000000000000000 RDI: ffff88805ef4e2e8 RBP: 0000000000000040 R08: 0000000000000000 R09: fffff5200067ae9a R10: ffffed100e0e0000 R11: 0000000000000001 R12: 0000000000000000 R13: ffffc900033d74d0 R14: 0000000000000000 R15: dffffc0000000000 FS: 00007f5c2a506700(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5c28bfe718 CR3: 000000005eea2000 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:3727 __dev_xmit_skb net/core/dev.c:3816 [inline] __dev_queue_xmit+0x198e/0x2fa0 net/core/dev.c:4141 __bpf_tx_skb net/core/filter.c:2113 [inline] __bpf_redirect_no_mac net/core/filter.c:2138 [inline] __bpf_redirect+0x6f2/0xdd0 net/core/filter.c:2161 ____bpf_clone_redirect net/core/filter.c:2428 [inline] bpf_clone_redirect+0x275/0x400 net/core/filter.c:2400 ___bpf_prog_run+0x2ece/0x7310 kernel/bpf/core.c:1835 __bpf_prog_run512+0x80/0xc0 kernel/bpf/core.c:2064 bpf_dispatcher_nop_func include/linux/bpf.h:804 [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:401 bpf_prog_test_run_skb+0xa0c/0x1cd0 net/bpf/test_run.c:1110 bpf_prog_test_run kernel/bpf/syscall.c:3369 [inline] __sys_bpf+0x105e/0x40d0 kernel/bpf/syscall.c:4681 __do_sys_bpf kernel/bpf/syscall.c:4767 [inline] __se_sys_bpf kernel/bpf/syscall.c:4765 [inline] __x64_sys_bpf+0x70/0xb0 kernel/bpf/syscall.c:4765 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+0x44/0xae RIP: 0033:0x7f5c29488a39 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:00007f5c2a506188 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 RAX: ffffffffffffffda RBX: 00007f5c2959bf60 RCX: 00007f5c29488a39 RDX: 0000000000000048 RSI: 0000000020000140 RDI: 000000000000000a RBP: 00007f5c294e2e8f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff5760926f R14: 00007f5c2a506300 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:ffffc900033d72f0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888070700000 RSI: 0000000000000000 RDI: ffff88805ef4e2e8 RBP: 0000000000000040 R08: 0000000000000000 R09: fffff5200067ae9a R10: ffffed100e0e0000 R11: 0000000000000001 R12: 0000000000000000 R13: ffffc900033d74d0 R14: 0000000000000000 R15: dffffc0000000000 FS: 00007f5c2a506700(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5c28bfe718 CR3: 000000005eea2000 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