bisecting fixing commit since 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14
building syzkaller on 749688d22abef3f3cb9a0480e15c19a3f2ed8e13
testing commit 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14 with gcc (GCC) 8.4.1 20210217
kernel signature: 0180fd39ca5fec088ded916417ff55d1a506bdeae6a6a9c65e40155816971cbe
run #0: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #1: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #2: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #3: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #4: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #5: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #6: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #7: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #8: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #9: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #10: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #11: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #12: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #13: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #14: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #15: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #16: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #17: crashed: KASAN: use-after-free Read in xfrm6_tunnel_destroy
run #18: OK
run #19: OK
testing current HEAD a6b2dae3ee3a3f9f4db3fab5b4b9e493fecf4acd
testing commit a6b2dae3ee3a3f9f4db3fab5b4b9e493fecf4acd with gcc (GCC) 8.4.1 20210217
kernel signature: 4107aba7cb691fa61201208070c172e52c79f1bc2ae468bbcd595284cbe46e1b
all runs: crashed: unregister_netdevice: waiting for DEV to become free
revisions tested: 2, total time: 36m32.903284309s (build: 20m16.843776874s, test: 15m3.29994727s)
the crash still happens on HEAD
commit msg: Linux 4.14.235
crash: unregister_netdevice: waiting for DEV to become free
unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1