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From: Zhihao Cheng <chengzhihao1@huawei.com>
To: Richard Weinberger <richard@nod.at>, Yu Hao <yhao016@ucr.edu>
Cc: 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>
Subject: Re: BUG: divide error in ubi_attach_mtd_dev
Date: Sun, 23 Apr 2023 11:20:55 +0800	[thread overview]
Message-ID: <ed510d18-47f1-7f46-03dd-84e043cab6d9@huawei.com> (raw)
In-Reply-To: <412779912.228444.1682023015809.JavaMail.zimbra@nod.at>

在 2023/4/21 4:36, Richard Weinberger 写道:
> ----- Ursprüngliche Mail -----
>>> 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/bzImage
>> -append “console=ttyS0 root=/dev/sda net.ifnames=0” -hda
>> /home/test/Workspace/SyzGen/linux-distro/image/stretch.img -chardev
>> socket,id=SOCKSYZ,server=on,nowait,host=localhost,port=54640 -mon
>> chardev=SOCKSYZ,mode=control -device virtio-rng-pci -device
>> e1000,netdev=net0 -netdev
>> user,id=net0,restrict=on,hostfwd=tcp:127.0.0.1:11760-:22 -display none
>> -serial stdio -cpu host,migratable=off -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 “mtdram test device”.
>>
>> root@syzkaller:~# cat /proc/mtd
>> dev:    size   erasesize  name
>> mtd0: 00020000 00001000 “mtdram test device”
> 
> Hmm, mtdram should be fine, erasesize is not zero.
> 

I guess the zero-erasesize mtd device is dynamically generated in 
runtime, after looking through the code, I find erasesize is 
initiallized in specific flash driver and it won't be updated later(eg. 
ioctl\sysctl). And some mtd devices may have zero erasesize, eg. 
drivers/mtd/devices/mchp23k256.c[1]. Unfortunately, I don't know how to 
load/simulate this mtd, maybe it requires a real device? If we load this 
mtd device as ubi, it will trigger the problem?


[1] https://cloud.tencent.com/developer/ask/sof/114616431

WARNING: multiple messages have this Message-ID (diff)
From: Zhihao Cheng <chengzhihao1@huawei.com>
To: Richard Weinberger <richard@nod.at>, Yu Hao <yhao016@ucr.edu>
Cc: 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>
Subject: Re: BUG: divide error in ubi_attach_mtd_dev
Date: Sun, 23 Apr 2023 11:20:55 +0800	[thread overview]
Message-ID: <ed510d18-47f1-7f46-03dd-84e043cab6d9@huawei.com> (raw)
In-Reply-To: <412779912.228444.1682023015809.JavaMail.zimbra@nod.at>

在 2023/4/21 4:36, Richard Weinberger 写道:
> ----- Ursprüngliche Mail -----
>>> 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/bzImage
>> -append “console=ttyS0 root=/dev/sda net.ifnames=0” -hda
>> /home/test/Workspace/SyzGen/linux-distro/image/stretch.img -chardev
>> socket,id=SOCKSYZ,server=on,nowait,host=localhost,port=54640 -mon
>> chardev=SOCKSYZ,mode=control -device virtio-rng-pci -device
>> e1000,netdev=net0 -netdev
>> user,id=net0,restrict=on,hostfwd=tcp:127.0.0.1:11760-:22 -display none
>> -serial stdio -cpu host,migratable=off -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 “mtdram test device”.
>>
>> root@syzkaller:~# cat /proc/mtd
>> dev:    size   erasesize  name
>> mtd0: 00020000 00001000 “mtdram test device”
> 
> Hmm, mtdram should be fine, erasesize is not zero.
> 

I guess the zero-erasesize mtd device is dynamically generated in 
runtime, after looking through the code, I find erasesize is 
initiallized in specific flash driver and it won't be updated later(eg. 
ioctl\sysctl). And some mtd devices may have zero erasesize, eg. 
drivers/mtd/devices/mchp23k256.c[1]. Unfortunately, I don't know how to 
load/simulate this mtd, maybe it requires a real device? If we load this 
mtd device as ubi, it will trigger the problem?


[1] https://cloud.tencent.com/developer/ask/sof/114616431

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Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

  reply	other threads:[~2023-04-23  3:21 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-18  5:10 BUG: divide error in ubi_attach_mtd_dev Yu Hao
2023-04-18  5:16 ` Yu Hao
2023-04-18  5:16   ` Yu Hao
2023-04-18  6:30   ` Richard Weinberger
2023-04-18  6:30     ` Richard Weinberger
2023-04-20  4:49     ` Zhihao Cheng
2023-04-20  4:49       ` Zhihao Cheng
2023-04-20 17:27       ` Yu Hao
2023-04-20 17:27         ` Yu Hao
2023-04-20 17:33         ` Richard Weinberger
2023-04-20 17:33           ` Richard Weinberger
2023-04-20 18:14           ` Yu Hao
2023-04-20 18:14             ` Yu Hao
2023-04-20 20:36             ` Richard Weinberger
2023-04-20 20:36               ` Richard Weinberger
2023-04-23  3:20               ` Zhihao Cheng [this message]
2023-04-23  3:20                 ` Zhihao Cheng
2023-04-23  8:02                 ` Richard Weinberger
2023-04-23  8:02                   ` Richard Weinberger
2023-04-23  9:13                   ` Zhihao Cheng
2023-04-23  9:13                     ` Zhihao Cheng
2023-10-02 10:11                     ` Lee Jones
2023-10-02 10:11                       ` Lee Jones
2023-10-02 10:28                       ` Richard Weinberger
2023-10-02 10:28                         ` Richard Weinberger
2023-10-02 14:04                         ` Lee Jones
2023-10-02 14:04                           ` Lee Jones
2023-10-02 14:15                           ` Richard Weinberger
2023-10-02 14:15                             ` Richard Weinberger
2023-10-02 14:36                             ` Lee Jones
2023-10-02 14:36                               ` Lee Jones
2023-06-20  9:17 ` admamiac

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