bisecting cause commit starting from a68a0262abdaa251e12c53715f48e698a18ef402 building syzkaller on c090b4da255257841173fb4eb18c19d69b293180 testing commit a68a0262abdaa251e12c53715f48e698a18ef402 with gcc (GCC) 8.1.0 kernel signature: c050303259cf3f8f0a81aea6f505ac3897d3abec94c507d45083e11a2095ad8f all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.9 testing commit bbf5c979011a099af5dc76498918ed7df445635b with gcc (GCC) 8.1.0 kernel signature: 515f03a0aeeb133aa2b2f66b7fe0a9c57066848d91e7279ea1677c9a1e253520 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.8 testing commit bcf876870b95592b52519ed4aafcf9d95999bc9c with gcc (GCC) 8.1.0 kernel signature: 0261a6cb35e3849e99b6fb76bc5f35549f662b9bca66de0c03696d60dfe31b27 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.7 testing commit 3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162 with gcc (GCC) 8.1.0 kernel signature: f3397b652782618d9d3eb5d87f95da90d42790679e4cc2e4c0f8d9679708157b all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.6 testing commit 7111951b8d4973bda27ff663f2cf18b663d15b48 with gcc (GCC) 8.1.0 kernel signature: 699d7c9d5cada8a1e74a63c5498753e89bb4dfa242ab0232c18db348469f0ff3 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.5 testing commit d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 with gcc (GCC) 8.1.0 kernel signature: f6a07960c19bd7cff424f18cefe29d03a264037c16eb561e084814a963611835 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.4 testing commit 219d54332a09e8d8741c1e1982f5eae56099de85 with gcc (GCC) 8.1.0 kernel signature: c0830d035a572aeeee865ff079e6a5b6b7992fe3e7b1ff162518c074ce6ecfd7 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.3 testing commit 4d856f72c10ecb060868ed10ff1b1453943fc6c8 with gcc (GCC) 8.1.0 kernel signature: 23cacfd634f8db51b97c2d204b661c1fc6f5787c270bcab3d30375ced88d8ed1 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.2 testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0 kernel signature: 0e40c4f275f3b9698e2bebb49f83aaf2f2c861c682793205d3a552e2cbcbda00 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.1 testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0 kernel signature: 58e80b83d6ea9dae79440eb5e76bf1e2ce108bcae4d7138b8b6e124c87b8fc44 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in __lookup_slow testing release v5.0 testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0 kernel signature: 9d56232dc6778736bc383ca32f8eb988284d6c41153fe5b264f87a801a393062 run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len run #2: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len run #7: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.20 testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0 kernel signature: 0c86900e33f1f2198a37b6c9280c6fe6ecf01d8b2b22d51091bdac5bfd463484 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.19 testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0 kernel signature: 51f42ae14fe5232c5086e8d1ce0269b8203924c3a17f105d06a3b0c4941fc705 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.18 testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0 kernel signature: 1097a5233289b95c386cada84bc278fa20da560e1da8185d366a7f1c8d69fa2b all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.17 testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0 kernel signature: b8eb82767e6012b26523d6b7d0542d61f160b3288701a279dd8713ee62bac487 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.16 testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0 kernel signature: e819695dd30cf845c7372c4cb41e18aab77cca0c8eec1c9fae476b5101cc6976 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.15 testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0 kernel signature: 46ad181363111f7ff4c2cc0de708e9bbf38630481286faa2ae722196536ebdc1 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.14 testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0 kernel signature: 35496ca6459b2542c25a0316cf8b8721a35a4e0df9b11fe2f7682bdab355167d all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.13 testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0 kernel signature: 102f9f4bdcf1bd43726760c9cba57a42a209b0232c16607973ec6937e0c79710 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.12 testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0 kernel signature: 82a3a761be5ee8f2b69ab8e61cd6c6eee50fba8f4de450e12b2933b917bcdb56 all runs: basic kernel testing failed: BUG: sleeping function called from invalid context in tap_get_minor testing release v4.11 testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0 kernel signature: 811b715c6613e853300ae1fcfbe30443d55feba1f28c19a8c564cb1abf710756 all runs: basic kernel testing failed: BUG: sleeping function called from invalid context in tap_get_minor testing release v4.10 testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0 kernel signature: 8a93ba6044f21d6d27bfbba28920a21e4042740766ceda296c88390cff6711a8 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.9 testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0 kernel signature: bfc5a4f5043be40b9901dadeadcf1e38c8a2d8dfcfa64aa36bb042f35d6bde10 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.8 testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0 kernel signature: eefcac8623acbec4eb491527b378079c04e411275f942570678cb17f4020d6f6 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.7 testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0 kernel signature: b1bb27f5ca1c62c9aa503c7b98e61f7f774ec6c7553340df8c82a5b40e73516a all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in lookup_one_len testing release v4.6 testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0 kernel signature: 95c3d6d46b0f4765b916d29f94027615ecfd90cb9c7348e8edb379669284b021 all runs: crashed: WARNING in sysfs_warn_dup revisions tested: 26, total time: 3h19m52.314673408s (build: 2h3m9.48610497s, test: 1h12m25.741189321s) the crash already happened on the oldest tested release commit msg: Linux 4.6 crash: WARNING in sysfs_warn_dup bond0: Enslaving bond_slave_1 as an active interface with an up link IPv6: ADDRCONF(NETDEV_UP): bridge_slave_0: link is not ready IPv6: ADDRCONF(NETDEV_UP): bridge0: link is not ready IPv6: ADDRCONF(NETDEV_UP): bridge_slave_1: link is not ready ------------[ cut here ]------------ WARNING: CPU: 1 PID: 7949 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x7b/0xa0 fs/sysfs/dir.c:30 sysfs: cannot create duplicate filename '/class/macvtap/tap50' Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 7949 Comm: syz-executor.3 Not tainted 4.6.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 ffff8800b1146fc8 ffffffff82da4dd2 ffffffff8667aec0 ffff8800b11470a0 ffffffff8672c900 ffffffff818db72b 0000000000000009 ffff8800b1147090 ffffffff815c7a54 0000000041b58ab3 ffffffff8778de63 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0x136/0x1d4 lib/dump_stack.c:51 [] panic+0x1af/0x348 kernel/panic.c:152 [] __warn+0x18d/0x1b0 kernel/panic.c:504 [] warn_slowpath_fmt+0x92/0xb0 kernel/panic.c:527 [] sysfs_warn_dup+0x7b/0xa0 fs/sysfs/dir.c:30 [] sysfs_do_create_link_sd.isra.0+0xd1/0xf0 fs/sysfs/symlink.c:51 [] sysfs_do_create_link fs/sysfs/symlink.c:80 [inline] [] sysfs_create_link+0x43/0xb0 fs/sysfs/symlink.c:92 [] device_add_class_symlinks drivers/base/core.c:891 [inline] [] device_add+0x6a1/0x1400 drivers/base/core.c:1086 [] device_create_groups_vargs+0x1c8/0x220 drivers/base/core.c:1709 [] device_create_vargs drivers/base/core.c:1749 [inline] [] device_create+0x88/0xa0 drivers/base/core.c:1785 [] macvtap_device_event+0x1c4/0x2a0 drivers/net/macvtap.c:1298 [] notifier_call_chain+0x8b/0x170 kernel/notifier.c:93 [] __raw_notifier_call_chain kernel/notifier.c:394 [inline] [] raw_notifier_call_chain+0x11/0x20 kernel/notifier.c:401 [] call_netdevice_notifiers_info+0x47/0x80 net/core/dev.c:1643 [] call_netdevice_notifiers net/core/dev.c:1659 [inline] [] register_netdevice+0x8e8/0xd00 net/core/dev.c:7027 [] macvlan_common_newlink+0x8b9/0x1090 drivers/net/macvlan.c:1316 [] macvtap_newlink+0xbf/0x110 drivers/net/macvtap.c:471 [] rtnl_newlink+0xd4b/0x1230 net/core/rtnetlink.c:2466 [] rtnetlink_rcv_msg+0x222/0x680 net/core/rtnetlink.c:3513 [] netlink_rcv_skb+0x242/0x350 net/netlink/af_netlink.c:2277 [] rtnetlink_rcv+0x25/0x30 net/core/rtnetlink.c:3519 [] netlink_unicast_kernel net/netlink/af_netlink.c:1214 [inline] [] netlink_unicast+0x3da/0x560 net/netlink/af_netlink.c:1240 [] netlink_sendmsg+0x9bb/0xb40 net/netlink/af_netlink.c:1786 [] sock_sendmsg_nosec net/socket.c:612 [inline] [] sock_sendmsg+0xb5/0xf0 net/socket.c:622 [] SYSC_sendto net/socket.c:1648 [inline] [] SyS_sendto+0x1ca/0x290 net/socket.c:1616 [] entry_SYSCALL_64_fastpath+0x23/0xc1 Kernel Offset: disabled