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Message-Id: <20231220091240.655350-1-miquel.raynal@bootlin.com>
Date: Wed, 20 Dec 2023 10:12:40 +0100
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: ZhaoLong Wang <wangzhaolong1@...wei.com>,
miquel.raynal@...tlin.com,
richard@....at,
vigneshr@...com,
dpervushin@...eddedalley.com,
Artem.Bityutskiy@...ia.com
Cc: linux-mtd@...ts.infradead.org,
linux-kernel@...r.kernel.org,
chengzhihao1@...wei.com,
yi.zhang@...wei.com,
yangerkun@...wei.com
Subject: Re: [PATCH V4] mtd: Fix gluebi NULL pointer dereference caused by ftl notifier
On Wed, 2023-12-20 at 02:46:19 UTC, ZhaoLong Wang wrote:
> If both ftl.ko and gluebi.ko are loaded, the notifier 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],
>
> In the normal case, obtain gluebi->desc in the gluebi_get_device(),
> and access gluebi->desc in the gluebi_read(). However,
> gluebi_get_device() is not executed in advance in the
> ftl_add_mtd() process, which leads to NULL pointer dereference.
>
> 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 the mtdblock device after creating mtd partition of the
> type MTD_UBIVOLUME.
>
> 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@...wei.com>
> Reviewed-by: Zhihao Cheng <chengzhihao1@...wei.com>
> Acked-by: Richard Weinberger <richard@....at>
Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.
Miquel
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