bisecting fixing commit since 5b7a52cd2eef952cee8a72512ef370bcdef46636 building syzkaller on a7aac492ebbc53e5c7bc4b5bbaf55f428c54093f testing commit 5b7a52cd2eef952cee8a72512ef370bcdef46636 with gcc (GCC) 8.4.1 20210217 kernel signature: 70efc7ba6adb49f16bd8e87a6e13f22dc7b70ce005652dfdf2d73e3b19e8d995 run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #1: crashed: BUG: unable to handle kernel run #2: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #7: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #10: crashed: BUG: unable to handle kernel run #11: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #12: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #13: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #14: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #15: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #16: crashed: BUG: unable to handle kernel run #17: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #18: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #19: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection testing current HEAD 96afcb20f36f07683aaa342e592ea8ec76fd1fa6 testing commit 96afcb20f36f07683aaa342e592ea8ec76fd1fa6 with gcc (GCC) 8.4.1 20210217 kernel signature: 7a05a33983a93bd927d484a0d11cc7c7df7bb424ef284b17fd96fa982e774fea all runs: crashed: unregister_netdevice: waiting for DEV to become free revisions tested: 2, total time: 22m35.68313371s (build: 15m28.012089322s, test: 6m20.474566332s) the crash still happens on HEAD commit msg: Linux 4.14.233 crash: unregister_netdevice: waiting for DEV to become free Bluetooth: hci4 command 0x0409 tx timeout Bluetooth: hci3 command 0x0409 tx timeout Bluetooth: hci5 command 0x0409 tx timeout Bluetooth: hci2 command 0x0409 tx timeout Bluetooth: hci0 command 0x0409 tx timeout unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1 Bluetooth: hci2 command 0x041b tx timeout Bluetooth: hci0 command 0x041b tx timeout Bluetooth: hci5 command 0x041b tx timeout Bluetooth: hci3 command 0x041b tx timeout Bluetooth: hci1 command 0x041b tx timeout Bluetooth: hci4 command 0x041b tx timeout Bluetooth: hci4 command 0x040f tx timeout Bluetooth: hci1 command 0x040f tx timeout Bluetooth: hci3 command 0x040f tx timeout Bluetooth: hci5 command 0x040f tx timeout Bluetooth: hci0 command 0x040f tx timeout Bluetooth: hci2 command 0x040f tx timeout Bluetooth: hci2 command 0x0419 tx timeout Bluetooth: hci0 command 0x0419 tx timeout Bluetooth: hci5 command 0x0419 tx timeout Bluetooth: hci3 command 0x0419 tx timeout Bluetooth: hci1 command 0x0419 tx timeout Bluetooth: hci4 command 0x0419 tx timeout