bisecting fixing commit since e7d2672c66e4d3675570369bf20856296da312c4 building syzkaller on a60cb4cd840ce786236a00480e8bb1025e0c5fef testing commit e7d2672c66e4d3675570369bf20856296da312c4 with gcc (GCC) 8.1.0 kernel signature: 86e2bb5b236bc1ac2358004c58e75f0a01131c419fced7b118c3fcda95959d42 all runs: crashed: general protection fault in hrtimer_active testing current HEAD b3a99fd385fab59d0b8b4fdfb449c1e979accab8 testing commit b3a99fd385fab59d0b8b4fdfb449c1e979accab8 with gcc (GCC) 8.1.0 kernel signature: 47bd8e9956712293543e1e03798fc024daae614b09167bbf4887c019e82dade7 all runs: crashed: general protection fault in cbs_destroy revisions tested: 2, total time: 25m24.387222264s (build: 17m54.096898319s, test: 6m40.253163794s) the crash still happens on HEAD commit msg: Linux 4.19.129 crash: general protection fault in cbs_destroy RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb3999536d4 R13: 00000000004c77fb R14: 00000000004dd098 R15: 0000000000000006 kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 7299 Comm: syz-executor.0 Not tainted 4.19.129-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__list_del_entry_valid+0x84/0xf3 lib/list_debug.c:51 Code: 0f 84 cc 00 00 00 48 b8 00 02 00 00 00 00 ad de 49 39 c4 0f 84 a5 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 5f 49 8b 14 24 48 39 da 0f 85 ba 00 00 00 49 8d 7d RSP: 0018:ffff888095b5f468 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff8880949719e0 RCX: ffffffff814d6c20 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880949719e8 RBP: ffff888095b5f480 R08: fffffbfff115de6d R09: fffffbfff115de6c R10: fffffbfff115de6c R11: ffffffff88aef363 R12: 0000000000000000 R13: 0000000000000000 R14: ffff888094971940 R15: ffff88809c64a380 FS: 00007fb399953700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000094bed000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __list_del_entry include/linux/list.h:117 [inline] list_del include/linux/list.h:125 [inline] cbs_destroy+0x7f/0x260 net/sched/sch_cbs.c:448 qdisc_create+0x9ce/0xf60 net/sched/sch_api.c:1203 tc_modify_qdisc+0x3f2/0x18f4 net/sched/sch_api.c:1571 rtnetlink_rcv_msg+0x34f/0x8f0 net/core/rtnetlink.c:4777 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2455 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4795 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x445/0x640 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x765/0xc50 net/netlink/af_netlink.c:1909 sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:632 ___sys_sendmsg+0x647/0x950 net/socket.c:2115 __sys_sendmsg+0xd9/0x180 net/socket.c:2153 __do_sys_sendmsg net/socket.c:2162 [inline] __se_sys_sendmsg net/socket.c:2160 [inline] __x64_sys_sendmsg+0x73/0xb0 net/socket.c:2160 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4598e9 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fb399952c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fb399952c90 RCX: 00000000004598e9 RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000003 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb3999536d4 R13: 00000000004c77fb R14: 00000000004dd098 R15: 0000000000000006 Modules linked in: ---[ end trace e6e74de88f497f98 ]--- RIP: 0010:__list_del_entry_valid+0x84/0xf3 lib/list_debug.c:51 Code: 0f 84 cc 00 00 00 48 b8 00 02 00 00 00 00 ad de 49 39 c4 0f 84 a5 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 5f 49 8b 14 24 48 39 da 0f 85 ba 00 00 00 49 8d 7d RSP: 0018:ffff888095b5f468 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff8880949719e0 RCX: ffffffff814d6c20 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880949719e8 RBP: ffff888095b5f480 R08: fffffbfff115de6d R09: fffffbfff115de6c R10: fffffbfff115de6c R11: ffffffff88aef363 R12: 0000000000000000 R13: 0000000000000000 R14: ffff888094971940 R15: ffff88809c64a380 FS: 00007fb399953700(0000) GS:ffff8880aeb00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000094bed000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400