Re: KASAN: null-ptr-deref Read in refcount_sub_and_test_checked (2)

[syzbot]

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

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13b0323b200000
start commit:   [unknown
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1070323b200000
console output: https://syzkaller.appspot.com/x/log.txt?x=17b0323b200000
dashboard link: https://syzkaller.appspot.com/bug?extid=0468b73bdbb243217224
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16d20893400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=118f5a2b400000

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