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Subject: Re: [PATCH v3] mtd: Fix gluebi NULL pointer dereference caused by ftl
 notifier
To:     ZhaoLong Wang <wangzhaolong1@huawei.com>,
        <miquel.raynal@bootlin.com>, <richard@nod.at>, <vigneshr@ti.com>,
        <Artem.Bityutskiy@nokia.com>, <dpervushin@embeddedalley.com>
CC:     <linux-mtd@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <yi.zhang@huawei.com>, <yangerkun@huawei.com>
References: <20231027012033.50280-1-wangzhaolong1@huawei.com>
From:   Zhihao Cheng <chengzhihao1@huawei.com>
Message-ID: <04a142af-a4e6-bb2c-fb92-61fc1df8ed98@huawei.com>
Date:   Fri, 27 Oct 2023 11:23:34 +0800
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在 2023/10/27 9:20, ZhaoLong Wang 写道:
> If both flt.ko and gluebi.ko are loaded, the notiier of ftl
> triggers NULL pointer dereference when trying to access
> ‘gluebi->desc’ in gluebi_read().
>
> ubi_gluebi_init
>    ubi_register_volume_notifier
>      ubi_enumerate_volumes
>        ubi_notify_all
>          gluebi_notify    nb->notifier_call()
>            gluebi_create
>              mtd_device_register
>                mtd_device_parse_register
>                  add_mtd_device
>                    blktrans_notify_add   not->add()
>                      ftl_add_mtd         tr->add_mtd()
>                        scan_header
>                          mtd_read
>                            mtd_read_oob
>                              mtd_read_oob_std
>                                gluebi_read   mtd->read()
>                                  gluebi->desc - NULL
>
> Detailed reproduction information available at the link[1],
>
> The solution for the gluebi module is to run jffs2 on the UBI
> volume without considering working with ftl or mtdblock.[2].
> Therefore, this problem can be avoided by preventing gluebi
> from creating mtdblock devices.
>
> Fixes: 2ba3d76a1e29 ("UBI: make gluebi a separate module")
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=217992 [1]
> Link: https://lore.kernel.org/lkml/441107100.23734.1697904580252.JavaMail.zimbra@nod.at/ [2]
> Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com>
> ---
>   drivers/mtd/mtd_blkdevs.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>