bisecting fixing commit since f56f3d0e65adb447b8b583c8ed4fbbe544c9bfde building syzkaller on 598ca6c8b8766304c3b2865e38f5f301c39bd299 testing commit f56f3d0e65adb447b8b583c8ed4fbbe544c9bfde with gcc (GCC) 8.1.0 kernel signature: 0d7fd35230bef7fc33b258790401a9e7a24754d6ce171ec4e81341a4115946dd all runs: crashed: WARNING: refcount bug in sock_wfree testing current HEAD 98db2bf27b9ed2d5ed0b6c9c8a4bfcb127a19796 testing commit 98db2bf27b9ed2d5ed0b6c9c8a4bfcb127a19796 with gcc (GCC) 8.1.0 kernel signature: 386c8abdd5f7ee0c2b50223933805ce783ca79efcbfeb2138c50b7e2d6a8b2be all runs: crashed: WARNING: refcount bug in sock_wfree revisions tested: 2, total time: 25m35.81099108s (build: 18m28.946614059s, test: 6m25.060968321s) the crash still happens on HEAD commit msg: Linux 4.14.171 crash: WARNING: refcount bug in sock_wfree IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready refcount_t: underflow; use-after-free. IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready ------------[ cut here ]------------ WARNING: CPU: 0 PID: 7086 at lib/refcount.c:187 refcount_sub_and_test.cold.13+0x13/0x1c lib/refcount.c:187 IPv6: ADDRCONF(NETDEV_UP): team0: link is not ready Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 7086 Comm: syz-executor.1 Not tainted 4.14.171-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 panic+0x1b0/0x358 kernel/panic.c:183 8021q: adding VLAN 0 to HW filter on device team0 __warn.cold.8+0x25/0x2c kernel/panic.c:547 report_bug+0x1a4/0x1f3 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:177 [inline] do_error_trap+0x1bd/0x310 arch/x86/kernel/traps.c:295 8021q: adding VLAN 0 to HW filter on device bond0 IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314 IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963 IPv6: ADDRCONF(NETDEV_UP): team0: link is not ready RIP: 0010:refcount_sub_and_test.cold.13+0x13/0x1c lib/refcount.c:187 8021q: adding VLAN 0 to HW filter on device team0 RSP: 0018:ffff88808e437728 EFLAGS: 00010282 RAX: 0000000000000026 RBX: 0000000000008100 RCX: 0000000000000000 RDX: 0000000000000026 RSI: ffffffff868cf080 RDI: ffffed1011c86edc RBP: ffff88808e437738 R08: ffff888092b50988 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000008100 R13: ffff8880757629fc R14: ffffffff88352d20 R15: 0000000000000000 sock_wfree+0x9b/0x120 net/core/sock.c:1812 sctp_wfree+0x28b/0x5f0 net/sctp/socket.c:7829 IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready skb_release_head_state+0xfc/0x1f0 net/core/skbuff.c:616 skb_release_all+0xd/0x50 net/core/skbuff.c:629 __kfree_skb net/core/skbuff.c:645 [inline] consume_skb+0x84/0x2a0 net/core/skbuff.c:705 sctp_chunk_destroy net/sctp/sm_make_chunk.c:1442 [inline] sctp_chunk_put+0x150/0x230 net/sctp/sm_make_chunk.c:1469 sctp_chunk_free+0x3f/0x50 net/sctp/sm_make_chunk.c:1456 __sctp_outq_teardown+0x1a2/0xe10 net/sctp/outqueue.c:228 IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready sctp_outq_free+0x9/0x10 net/sctp/outqueue.c:284 sctp_association_free+0x1d5/0x711 net/sctp/associola.c:358 sctp_cmd_delete_tcb net/sctp/sm_sideeffect.c:924 [inline] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1312 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1179 [inline] sctp_do_sm+0xea4/0x4dd0 net/sctp/sm_sideeffect.c:1150 IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready IPv6: ADDRCONF(NETDEV_UP): veth0_to_team: link is not ready IPv6: ADDRCONF(NETDEV_UP): veth1_to_team: link is not ready sctp_primitive_ABORT+0x7c/0xc0 net/sctp/primitive.c:119 hsr0: Slave A (hsr_slave_0) is not up; please bring it up to get a fully working HSR network sctp_close+0x23e/0x710 net/sctp/socket.c:1560 inet_release+0xd9/0x1c0 net/ipv4/af_inet.c:425 __sock_release+0xc2/0x2a0 net/socket.c:602 sock_close+0x10/0x20 net/socket.c:1139 __fput+0x232/0x750 fs/file_table.c:210 ____fput+0x9/0x10 fs/file_table.c:244 task_work_run+0xe5/0x170 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x16a/0x1b0 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline] syscall_return_slowpath arch/x86/entry/common.c:270 [inline] do_syscall_64+0x416/0x5b0 arch/x86/entry/common.c:297 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4141d1 RSP: 002b:00007fffc2adbcd0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00000000004141d1 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006 RBP: 0000000000000001 R08: ffffffffffffffff R09: ffffffffffffffff R10: 00007fffc2adbdb0 R11: 0000000000000293 R12: 000000000075bf20 R13: 000000000000cdf5 R14: 0000000000761400 R15: 000000000075bf2c Kernel Offset: disabled Rebooting in 86400 seconds..