linux-kernel - Re: [PATCH] erofs: do sanity check on m->type in z_erofs_load_compact

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Message-ID: <e759af7b-0aef-4f3e-a84b-91a24602b32c@huawei.com>
Date: Tue, 8 Jul 2025 10:45:19 +0800
From: Hongbo Li <lihongbo22@...wei.com>
To: Gao Xiang <hsiangkao@...ux.alibaba.com>, Chao Yu <chao@...nel.org>,
	<xiang@...nel.org>
CC: <linux-erofs@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>, Yue Hu
	<zbestahu@...il.com>, Jeffle Xu <jefflexu@...ux.alibaba.com>, Sandeep Dhavale
	<dhavale@...gle.com>
Subject: Re: [PATCH] erofs: do sanity check on m->type in
 z_erofs_load_compact_lcluster()



On 2025/7/8 10:35, Gao Xiang wrote:
> 
> 
> On 2025/7/8 10:30, Hongbo Li wrote:
>>
>>
>> On 2025/7/7 16:47, Chao Yu wrote:
>>> All below functions will do sanity check on m->type, let's move sanity
>>> check to z_erofs_load_compact_lcluster() for cleanup.
>>> - z_erofs_map_blocks_fo
>>> - z_erofs_get_extent_compressedlen
>>> - z_erofs_get_extent_decompressedlen
>>> - z_erofs_extent_lookback
>>>
>>> Signed-off-by: Chao Yu <chao@...nel.org>
>>> ---
>>>   fs/erofs/zmap.c | 60 ++++++++++++++++++-------------------------------
>>>   1 file changed, 22 insertions(+), 38 deletions(-)
>>>
>>> diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
>>> index 0bebc6e3a4d7..e530b152e14e 100644
>>> --- a/fs/erofs/zmap.c
>>> +++ b/fs/erofs/zmap.c
>>> @@ -240,6 +240,13 @@ static int z_erofs_load_compact_lcluster(struct 
>>> z_erofs_maprecorder *m,
>>>   static int z_erofs_load_lcluster_from_disk(struct 
>>> z_erofs_maprecorder *m,
>>>                          unsigned int lcn, bool lookahead)
>>>   {
>>> +    if (m->type >= Z_EROFS_LCLUSTER_TYPE_MAX) {
>>> +        erofs_err(m->inode->i_sb, "unknown type %u @ lcn %u of nid 
>>> %llu",
>>> +                m->type, lcn, EROFS_I(m->inode)->nid);
>>> +        DBG_BUGON(1);
>>> +        return -EOPNOTSUPP;
>>> +    }
>>> +
>>
>> Hi, Chao,
>>
>> After moving the condition in here, there is no need to check in 
>> z_erofs_extent_lookback, z_erofs_get_extent_compressedlen and 
>> z_erofs_get_extent_decompressedlen. Because in z_erofs_map_blocks_fo, 
>> the condition has been checked in before. Right?
> 
> I've replied some similar question.
> 
> Because z_erofs_get_extent_compressedlen and 
> z_erofs_get_extent_decompressedlen()
> use the different lcn (lcluster) against z_erofs_map_blocks_fo().
> 
> So if a new lcn(lcluster number) is loaded, we'd check if the type is 
> valid.
> 
Ok, the type will change after loading.

Thanks,
Hongbo

> Thanks,
> Gao Xiang
>