bisecting fixing commit since e7d2672c66e4d3675570369bf20856296da312c4 building syzkaller on a60cb4cd840ce786236a00480e8bb1025e0c5fef testing commit e7d2672c66e4d3675570369bf20856296da312c4 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: c8d7d6ef9132a831bde9eec8ec6b306028d437f97e20ed614f55f7a2cd70fd74 all runs: crashed: general protection fault in hrtimer_active testing current HEAD 2950c9c5e0df6bd34af45a5168bbee345e95eae2 testing commit 2950c9c5e0df6bd34af45a5168bbee345e95eae2 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 2736844a2149a83721b8d078723b784cf9d6134ce804e6a798818cf656a9ffe4 all runs: crashed: general protection fault in cbs_destroy revisions tested: 2, total time: 27m22.740048725s (build: 20m7.858572666s, test: 6m23.627303079s) the crash still happens on HEAD commit msg: Linux 4.19.207 crash: general protection fault in cbs_destroy RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000006 R13: 00000000004f5b78 R14: 00000000004b34d0 R15: 00007ff1d49a46bc 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: 0 PID: 6584 Comm: syz-executor.1 Not tainted 4.19.207-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__list_del_entry_valid+0x84/0x100 lib/list_debug.c:51 Code: 0f 84 9c 6e 88 03 48 b8 00 02 00 00 00 00 ad de 49 39 c4 0f 84 75 6e 88 03 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 8a 6e 88 03 49 8d 7d RSP: 0018:ffff8881e45f7460 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff8881e44ac320 RCX: ffffffff814c2960 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8881e44ac328 RBP: ffff8881e45f7478 R08: fffffbfff115e701 R09: fffffbfff115e700 R10: fffffbfff115e700 R11: ffffffff88af3803 R12: 0000000000000000 R13: 0000000000000000 R14: ffff8881e44ac280 R15: ffff8881edb08440 FS: 00007ff1d49a4700(0000) GS:ffff8881f6800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fadee56f000 CR3: 00000001d136b003 CR4: 00000000001606f0 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+0x9c9/0xf60 net/sched/sch_api.c:1204 tc_modify_qdisc+0x3f2/0x18f0 net/sched/sch_api.c:1572 rtnetlink_rcv_msg+0x34f/0x8f0 net/core/rtnetlink.c:4782 netlink_rcv_skb+0x13e/0x3d0 net/netlink/af_netlink.c:2457 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4800 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] netlink_unicast+0x445/0x640 net/netlink/af_netlink.c:1346 netlink_sendmsg+0x764/0xc70 net/netlink/af_netlink.c:1911 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xb5/0xf0 net/socket.c:661 ___sys_sendmsg+0x647/0x950 net/socket.c:2227 __sys_sendmsg+0xd9/0x180 net/socket.c:2265 __do_sys_sendmsg net/socket.c:2274 [inline] __se_sys_sendmsg net/socket.c:2272 [inline] __x64_sys_sendmsg+0x73/0xb0 net/socket.c:2272 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4611a9 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:00007ff1d49a41a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000052bf00 RCX: 00000000004611a9 RDX: 0000000000000000 RSI: 0000000020000240 RDI: 0000000000000003 RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000006 R13: 00000000004f5b78 R14: 00000000004b34d0 R15: 00007ff1d49a46bc Modules linked in: ---[ end trace 1fb954de95374c92 ]--- RIP: 0010:__list_del_entry_valid+0x84/0x100 lib/list_debug.c:51 Code: 0f 84 9c 6e 88 03 48 b8 00 02 00 00 00 00 ad de 49 39 c4 0f 84 75 6e 88 03 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 8a 6e 88 03 49 8d 7d RSP: 0018:ffff8881e45f7460 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff8881e44ac320 RCX: ffffffff814c2960 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8881e44ac328 RBP: ffff8881e45f7478 R08: fffffbfff115e701 R09: fffffbfff115e700 R10: fffffbfff115e700 R11: ffffffff88af3803 R12: 0000000000000000 R13: 0000000000000000 R14: ffff8881e44ac280 R15: ffff8881edb08440 FS: 00007ff1d49a4700(0000) GS:ffff8881f6800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fadee56f000 CR3: 00000001d136b003 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 0f 84 9c 6e 88 03 je 0x3886ea2 6: 48 b8 00 02 00 00 00 movabs $0xdead000000000200,%rax d: 00 ad de 10: 49 39 c4 cmp %rax,%r12 13: 0f 84 75 6e 88 03 je 0x3886e8e 19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 20: fc ff df 23: 4c 89 e2 mov %r12,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2e: 75 5f jne 0x8f 30: 49 8b 14 24 mov (%r12),%rdx 34: 48 39 da cmp %rbx,%rdx 37: 0f 85 8a 6e 88 03 jne 0x3886ec7 3d: 49 rex.WB 3e: 8d .byte 0x8d 3f: 7d .byte 0x7d