Bisection is inconclusive: the bug happens on the oldest tested release.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=14fb90ef200000
start commit:   [unknown
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=16fb90ef200000
console output: https://syzkaller.appspot.com/x/log.txt?x=12fb90ef200000
dashboard link: https://syzkaller.appspot.com/bug?extid=55f9d3e51d49e20b2ce5
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=109c886cc00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11ed20d0c00000

For information about bisection process see: https://goo.gl/tpsmEJ#bisection