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From:   Yu Hao <yhao016@ucr.edu>
Date:   Thu, 20 Apr 2023 11:14:04 -0700
Message-ID: <CA+UBctA4fSbSdooQ9q9fwNuaHb_PnkfFuqJ7Q5vii-3-uCiUjw@mail.gmail.com>
Subject: Re: BUG: divide error in ubi_attach_mtd_dev
To:     Richard Weinberger <richard@nod.at>
Cc:     chengzhihao1 <chengzhihao1@huawei.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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On Thu, Apr 20, 2023 at 10:33=E2=80=AFAM Richard Weinberger <richard@nod.at=
> wrote:
>
> ----- Urspr=C3=BCngliche Mail -----
> > The kernel is in qemu. We find that the `mtd` is from
> > `mtd =3D get_mtd_device(NULL, req.mtd_num);` in function `ctrl_cdev_ioc=
tl`.
> > And we are still trying to figure out what MTD is.
>
> Can you please share the qemu command line?
>

qemu-system-x86_64 -m 2G -smp 2 -kernel
/home/test/Workspace/SyzGen/linux-distro/linux-6.2-debug/arch/x86/boot/bzIm=
age
-append =E2=80=9Cconsole=3DttyS0 root=3D/dev/sda net.ifnames=3D0=E2=80=9D -=
hda
/home/test/Workspace/SyzGen/linux-distro/image/stretch.img -chardev
socket,id=3DSOCKSYZ,server=3Don,nowait,host=3Dlocalhost,port=3D54640 -mon
chardev=3DSOCKSYZ,mode=3Dcontrol -device virtio-rng-pci -device
e1000,netdev=3Dnet0 -netdev
user,id=3Dnet0,restrict=3Don,hostfwd=3Dtcp:127.0.0.1:11760-:22 -display non=
e
-serial stdio -cpu host,migratable=3Doff -no-reboot -name VM -snapshot
-enable-kvm

> Within Linux you can query /proc/mtd or /sys/class/mtd/
> to get infos about the MTD in question.
>

Thanks for the hints. We find that this is a =E2=80=9Cmtdram test device=E2=
=80=9D.

root@syzkaller:~# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00020000 00001000 =E2=80=9Cmtdram test device=E2=80=9D

> Thanks,
> //richard
>