syzbot has bisected this issue to:
commit 5872331b3d91820e14716632ebb56b1399b34fe1
Author: Eric Sandeen <sandeen@xxxxxxxxxx>
Date: Wed Jun 17 19:19:04 2020 +0000
ext4: fix potential negative array index in do_split()
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15b9ce30580000
start commit: 2e1b3cc9d7f7 Merge tag 'arm-fixes-6.12-2' of git://git.ker..
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=17b9ce30580000
console output: https://syzkaller.appspot.com/x/log.txt?x=13b9ce30580000
kernel config: https://syzkaller.appspot.com/x/.config?x=921b01cbfd887a9b
dashboard link: https://syzkaller.appspot.com/bug?extid=0c99c3f90699936c1e77
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=173636a7980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1600cf40580000
Reported-by: syzbot+0c99c3f90699936c1e77@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 5872331b3d91 ("ext4: fix potential negative array index in do_split()")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
