bisecting cause commit starting from 0e5b36bc4c1fccfc18dd851d960781589c16dae8 building syzkaller on 040fda588472da50749a3f605e183ad5c02104f4 testing commit 0e5b36bc4c1fccfc18dd851d960781589c16dae8 with gcc (GCC) 8.1.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in tc_bind_tclass testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in tc_bind_tclass testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in tc_bind_tclass testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in tc_ctl_tclass testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in tc_ctl_tclass testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in tc_ctl_tclass testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in tc_ctl_tclass testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in tc_ctl_tclass testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in qdisc_hash_add testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in qdisc_hash_add testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in qdisc_hash_add testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in qdisc_hash_add testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 all runs: crashed: general protection fault in qdisc_hash_add testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0 all runs: crashed: divide error in red_change testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.5 testing commit b562e44f507e863c6792946e4e1b1449fbbac85d with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.4 testing commit afd2ff9b7e1b367172f18ba7f693dfb62bdcb2dc with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.3 testing commit 6a13feb9c82803e2b815eca72fa7a9f5561d7861 with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.2 testing commit 64291f7db5bd8150a74ad2036f1037e6a0428df2 with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change testing release v4.1 testing commit b953c0d234bc72e8489d3bf51a276c5c4ec85345 with gcc (GCC) 5.5.0 all runs: crashed: divide error in red_change revisions tested: 24, total time: 3h6m12.549694605s (build: 1h41m17.741790869s, test: 1h18m34.867731728s) the crash already happened on the oldest tested release crash: divide error in red_change chnl_net:caif_netlink_parms(): no params data found IPv6: ADDRCONF(NETDEV_UP): bond_slave_1: link is not ready bond0: Enslaving bond_slave_1 as an active interface with an up link 8021q: adding VLAN 0 to HW filter on device bond0 IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready divide error: 0000 [#1] PREEMPT SMP Modules linked in: CPU: 0 PID: 5480 Comm: syz-executor.4 Not tainted 4.1.0 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8800b88ae610 ti: ffff8800b79d8000 task.ti: ffff8800b79d8000 RIP: 0010:[] [] red_set_parms include/net/red.h:191 [inline] RIP: 0010:[] [] red_change+0x153/0x390 net/sched/sch_red.c:218 RSP: 0018:ffff8800b79db988 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8800b465cc00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff8800b79b7c34 RDI: 0000000000000001 RBP: ffff8800b79db9f8 R08: 0000000000000000 R09: ffffffff82e356c0 R10: 0000000000000000 R11: ffff8800b465cde0 R12: 0000000000000000 R13: ffff8800b79b7d34 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f176dec2700(0000) GS:ffff88012c000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000713388 CR3: 000000012a4e8000 CR4: 00000000001407f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Stack: 0000000000000000 ffff8800b79b7c34 ffff8800b465cd88 00000000842f4f00 0000000000000000 ffff8800b79b7d34 ffff8800b79b7c30 0000000000000000 ffff8800b79db9e8 ffff8800b465cc00 ffff8800b79b7c2c 00000000fffffff4 Call Trace: [] red_init+0x51/0x60 net/sched/sch_red.c:254 [] qdisc_create+0xc9/0x4d0 net/sched/sch_api.c:949 [] tc_modify_qdisc+0x18e/0x660 net/sched/sch_api.c:1301 [] rtnetlink_rcv_msg+0x83/0x230 net/core/rtnetlink.c:3250 [] netlink_rcv_skb+0xa9/0xd0 net/netlink/af_netlink.c:2843 [] rtnetlink_rcv+0x29/0x40 net/core/rtnetlink.c:3256 [] netlink_unicast_kernel net/netlink/af_netlink.c:1763 [inline] [] netlink_unicast+0x1ca/0x2e0 net/netlink/af_netlink.c:1789 [] netlink_sendmsg+0x310/0x3d0 net/netlink/af_netlink.c:2353 [] sock_sendmsg_nosec net/socket.c:613 [inline] [] sock_sendmsg+0x35/0x40 net/socket.c:623 [] ___sys_sendmsg+0x2c3/0x2d0 net/socket.c:1955 [] __sys_sendmsg+0x3d/0x80 net/socket.c:1989 [] SYSC_sendmsg net/socket.c:2000 [inline] [] SyS_sendmsg+0xd/0x20 net/socket.c:1996 [] system_call_fastpath+0x16/0x7a Code: 00 00 75 19 41 bc ff ff ff ff 89 f9 44 89 e0 d3 e8 40 80 ff 1f 44 0f 46 e0 45 0f af e0 31 d2 44 89 e0 bf 01 00 00 00 48 89 75 98 <41> f7 f0 44 89 a3 ec 01 00 00 4c 89 5d a0 44 88 55 ab 85 c0 0f RIP [] red_set_parms include/net/red.h:191 [inline] RIP [] red_change+0x153/0x390 net/sched/sch_red.c:218 RSP ---[ end trace a46a07040790e7eb ]---