bisecting fixing commit since dda0e2920330128e0dbdeb11c8f25031aa40b11c building syzkaller on 5ed396e666c7826bed46f06c4db1409376691fed testing commit dda0e2920330128e0dbdeb11c8f25031aa40b11c with gcc (GCC) 8.1.0 kernel signature: 135189f87ee39be6cc7e3acabbcc47071377487913e3689c2c3b764728719ebd run #0: crashed: WARNING in ip_rt_bug run #1: crashed: WARNING in ip_rt_bug run #2: crashed: WARNING in ip_rt_bug run #3: crashed: WARNING in corrupted run #4: crashed: WARNING in corrupted run #5: crashed: WARNING in corrupted run #6: crashed: WARNING in ip_rt_bug run #7: crashed: WARNING in ip_rt_bug run #8: crashed: WARNING in corrupted run #9: crashed: WARNING in ip_rt_bug testing current HEAD 399849e4654ea496a6217ba4e5ee3d304c995ab4 testing commit 399849e4654ea496a6217ba4e5ee3d304c995ab4 with gcc (GCC) 8.1.0 kernel signature: c2e9dc57dd7c4d2a5d924c25f00b6f9314ed12cd77392c74231008158732cfe3 run #0: crashed: WARNING in corrupted run #1: crashed: WARNING in ip_rt_bug run #2: crashed: WARNING in corrupted run #3: crashed: WARNING in corrupted run #4: crashed: WARNING in corrupted run #5: crashed: WARNING in corrupted run #6: crashed: WARNING in corrupted run #7: crashed: WARNING in corrupted run #8: crashed: WARNING in ip_rt_bug run #9: crashed: WARNING in ip_rt_bug revisions tested: 2, total time: 23m58.960747s (build: 17m12.982310844s, test: 6m15.553115682s) the crash still happens on HEAD commit msg: Linux 4.19.131 crash: WARNING in ip_rt_bug device veth0_macvtap entered promiscuous mode IPv6: ADDRCONF(NETDEV_UP): macvtap0: link is not ready device veth1_macvtap entered promiscuous mode IPv6: ADDRCONF(NETDEV_UP): macsec0: link is not ready ------------[ cut here ]------------ WARNING: CPU: 0 PID: 7865 at net/ipv4/route.c:1234 ip_rt_bug+0x18/0x20 net/ipv4/route.c:1234 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 7865 Comm: syz-executor.5 Not tainted 4.19.131-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 panic+0x1cd/0x375 kernel/panic.c:186 __warn.cold.8+0x1b/0x3e kernel/panic.c:541 report_bug+0x1a4/0x200 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:178 [inline] do_error_trap+0x200/0x350 arch/x86/kernel/traps.c:296 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038 RIP: 0010:ip_rt_bug+0x18/0x20 net/ipv4/route.c:1234 Code: 48 8b 45 d8 e9 ed fe ff ff 66 0f 1f 84 00 00 00 00 00 55 48 89 d7 48 89 e5 e8 94 d4 a2 ff 48 c7 c7 40 a3 c6 87 e8 38 22 90 fb <0f> 0b 31 c0 5d c3 66 90 48 b8 00 00 00 00 00 fc ff df 48 89 fa 55 RSP: 0018:ffff888081c37120 EFLAGS: 00010282 RAX: 0000000000000024 RBX: ffff888081e5b980 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff87678f00 RDI: ffffffff8a189960 RBP: ffff888081c37120 R08: ffffed1015d45079 R09: ffffed1015d45078 R10: ffffed1015d45078 R11: ffff8880aea283c7 R12: ffff88808ecfc100 R13: ffff8880864f7280 R14: ffff888081e5b9d8 R15: ffff888081c373d4 dst_output include/net/dst.h:447 [inline] ip_local_out+0x74/0x130 net/ipv4/ip_output.c:124 ip_send_skb+0x36/0xa0 net/ipv4/ip_output.c:1446 ip_push_pending_frames+0x4d/0x70 net/ipv4/ip_output.c:1466 icmp_push_reply+0x383/0x610 net/ipv4/icmp.c:395 __icmp_send+0xbc7/0x1930 net/ipv4/icmp.c:744 icmp_send include/net/icmp.h:47 [inline] ip_options_compile+0xad/0xc0 net/ipv4/ip_options.c:485 ip_rcv_options net/ipv4/ip_input.c:282 [inline] ip_rcv_finish_core.isra.16+0x3b1/0x1830 net/ipv4/ip_input.c:356 ip_rcv_finish+0x104/0x270 net/ipv4/ip_input.c:412 NF_HOOK include/linux/netfilter.h:289 [inline] ip_rcv+0xcb/0x2e0 net/ipv4/ip_input.c:524 __netif_receive_skb_one_core+0x112/0x1a0 net/core/dev.c:4954 __netif_receive_skb+0x1f/0x1b0 net/core/dev.c:5066 netif_receive_skb_internal+0xca/0x300 net/core/dev.c:5156 netif_receive_skb+0x3b/0x1e0 net/core/dev.c:5213 tun_rx_batched.isra.54+0x4d2/0x9b0 drivers/net/tun.c:1535 tun_get_user+0x2606/0x48a0 drivers/net/tun.c:1966 tun_chr_write_iter+0xaf/0x150 drivers/net/tun.c:1995 call_write_iter include/linux/fs.h:1821 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x443/0x890 fs/read_write.c:487 vfs_write+0x150/0x4d0 fs/read_write.c:549 ksys_write+0x103/0x260 fs/read_write.c:599 __do_sys_write fs/read_write.c:611 [inline] __se_sys_write fs/read_write.c:608 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:608 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45c849 Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fa4bd139c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fa4bd13a6d4 RCX: 000000000045c849 RDX: 000000000000100c RSI: 0000000020000240 RDI: 0000000000000005 RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000000d0d R14: 00000000004cf379 R15: 000000000076bf0c Kernel Offset: disabled Rebooting in 86400 seconds..