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 <[email protected]>
>
> [ 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/[email protected]/
> [2]
> Signed-off-by: ZhaoLong Wang <[email protected]>
> Reviewed-by: Zhihao Cheng <[email protected]>
> Acked-by: Richard Weinberger <[email protected]>
> Signed-off-by: Miquel Raynal <[email protected]>
> Link:
> https://lore.kernel.org/linux-mtd/[email protected]
> Signed-off-by: Sasha Levin <[email protected]>
> ---
> 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/[email protected]/
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
在 2024/2/9 15:09, Martin Kepplinger-Novakovic 写道:
> 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 <[email protected]>
>>
>> [ Upstream commit a43bdc376deab5fff1ceb93dca55bcab8dbdc1d6 ]
>>
[...]
>> 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/[email protected]/
> 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.
>
This change does affect the mounting(mtdblock based on gluebi) behavior
in userspace. It was picked into stable versions because the fixed
problem is serious and easy to be reproduced, I guess.
A temporary solution is that modify mounting source target in userspace,
just replace mtdblock with mtd char device. For example, mount -t jffs2
mtd0 /mnt