Am Montag, dem 22.01.2024 um 15:56 -0800 schrieb Greg Kroah-Hartman:
> 5.4-stable review patch. If anyone has any objections, please let me
> know.
>
> ------------------
>
> From: ZhaoLong Wang <wangzhaolong1@xxxxxxxxxx>
>
> [ Upstream commit a43bdc376deab5fff1ceb93dca55bcab8dbdc1d6 ]
>
> 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@xxxxxx/
> [2]
> Signed-off-by: ZhaoLong Wang <wangzhaolong1@xxxxxxxxxx>
> Reviewed-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
> Acked-by: Richard Weinberger <richard@xxxxxx>
> Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> Link:
> https://lore.kernel.org/linux-mtd/20231220024619.2138625-1-wangzhaolong1@xxxxxxxxxx
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> drivers/mtd/mtd_blkdevs.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
> index 0c05f77f9b21..dd0d0bf5f57f 100644
> --- a/drivers/mtd/mtd_blkdevs.c
> +++ b/drivers/mtd/mtd_blkdevs.c
> @@ -533,7 +533,7 @@ static void blktrans_notify_add(struct mtd_info
> *mtd)
> {
> struct mtd_blktrans_ops *tr;
>
> - if (mtd->type == MTD_ABSENT)
> + if (mtd->type == MTD_ABSENT || mtd->type == MTD_UBIVOLUME)
> return;
>
> list_for_each_entry(tr, &blktrans_majors, list)
> @@ -576,7 +576,7 @@ int register_mtd_blktrans(struct mtd_blktrans_ops
> *tr)
> list_add(&tr->list, &blktrans_majors);
>
> mtd_for_each_device(mtd)
> - if (mtd->type != MTD_ABSENT)
> + if (mtd->type != MTD_ABSENT && mtd->type !=
> MTD_UBIVOLUME)
> tr->add_mtd(tr, mtd);
>
> mutex_unlock(&mtd_table_mutex);
Hi Greg, hi patch-developers,
wait a second. this already went into v5.4.268 but still: Doesn't this
break userspace?
According to
https://lore.kernel.org/lkml/441107100.23734.1697904580252.JavaMail.zimbra@xxxxxx/
where this solution seems to come from, the behaviour changes: "no
mtdblock (hence, also no FTLs) on top of gluebi."
I fell accross this because of an out-of-tree module that does
sys_mount() an mtdblock, so I won't complain about my code specifically
:) But doesn't it break mounting, say, jffs2 inside an ubi via
mtdblock? If so, is this really something that you want to see
backported to old kernels?
Or differently put: Has this patch been picked up for old stable
kernels by scripts or by a human?
I just want to make sure, and who knows, it might help others too, who
would just do a (possibly dangerous?) revert in their trees.
thanks!
martin
