Two bug fix commit fixes in the ubi_resize_volume() were fixed by a patch in the mailing list

[ZhaoLong Wang]

OK, I'll try to send a series later to fix these problems in the 
ubi_resize_volume().

Thanks for everyone.

ZhaoLong Wang

在 2023/4/6 9:20, Guo Xuenan 写道:
> Hi Richard，
>
> On 2023/4/6 4:48, Richard Weinberger wrote:
>> ----- Ursprüngliche Mail -----
>>> Von: "chengzhihao1" <chengzhihao1 at huawei.com>
>>>>       I'd like to know why patch[1] didn't get into the mainline.
>>>>
>>>> [1] 
>>>> http://patchwork.ozlabs.org/project/linux-mtd/patch/20220124024056.1996763-1-guoxuenan@huawei.com/
>> Sorry, it fell through the cracks.
>>
>>> I find there were three problems in ubi_resize_volume():
>>>
>>> 1. Memleak  - fixed by 1e591ea072df ("ubi: Fix unreferenced object
>>> reported by kmemleak in ubi_resize_volume()")
>> Agreed.
>>
>>> 2. UAF in error handling path  - fixed by 9af31d6ec1a4 ("ubi: Fix
>>> use-after-free when volume resizing failed")
>> Agreed.
>>
>>> 3. UAF in concurrent shring volume and writing
>>> fastmap(vol->reserved_pebs iteration)  - fixed by [1]
>>> 4. Potentional data lost in failed shrinking(failed after unmapping
>>> lebs)  - mentioned in [1], which is not a big problem, we can add some
>>> comments to explain it.
>>> 5. Too many lebs used if expanding volume failed after [1] applied:
>>> If we update vol->reserved_pebs together with vol->eba_tbl, then other
>>> writing process could take lnum bigger than old vol->reserved_pebs.
>>> There will be zombie logical pebs(lnum greater than vol->reserved_pebs,
>>> could not be accessed or reclaimed) if resizing failed.
>>> Maybe we should fix that by holding 'leb_write_lock' while expanding 
>>> volume?
>>> 6. In error handling path 'out_acc', UBI should recover 
>>> 'ubi->rsvd_pebs'
>>> and 'ubi->avail_pebs' in 'pebs > 0' case, otherwise UBI will display
>>> wrong available peb count.
>>>
>>> Richard, How do you think?
>> I agree, we should apply this patch. Guo Xuenan, can you please 
>> rebase your patch
>> on the latest kernel and resend?
>> vmt.c saw some changes and the patch does not longer apply.
> OK，I will ask my colleagues Zhaolong Wang to help me rebase and resend 
> it as soon as
> possible，he is currently more focused on ubifs :)
>
> Thanks
> Xuenan
>> Thanks,
>> //richard
>>
>