linux-kernel - Re: [PATCH] erofs: fix kvcalloc() misuse with __GFP

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Message-ID: <9f4c8bf0-db3e-b97a-504d-6015b75a2174@linux.alibaba.com>
Date:   Mon, 9 Jan 2023 20:55:08 +0800
From:   Gao Xiang <hsiangkao@...ux.alibaba.com>
To:     Chao Yu <chao@...nel.org>, linux-erofs@...ts.ozlabs.org,
        Yue Hu <huyue2@...lpad.com>,
        Jeffle Xu <jefflexu@...ux.alibaba.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        syzbot+c3729cda01706a04fb98@...kaller.appspotmail.com
Subject: Re: [PATCH] erofs: fix kvcalloc() misuse with __GFP_NOFAIL

Hi Chao,

On 2023/1/9 18:34, Chao Yu wrote:
> On 2023/1/6 13:06, Gao Xiang wrote:
>>
>>
>> On 2023/1/6 11:19, Gao Xiang wrote:
>>> As reported by syzbot [1], kvcalloc() cannot work with  __GFP_NOFAIL.
>>> Let's use kcalloc() instead.
>>>
>>> [1] https://lore.kernel.org/r/0000000000007796bd05f1852ec2@google.com
>>> Reported-by: syzbot+c3729cda01706a04fb98@...kaller.appspotmail.com
>>
>> Fixes: fe3e5914e6dc ("erofs: try to leave (de)compressed_pages on stack if possible")
>> Fixes: 4f05687fd703 ("erofs: introduce struct z_erofs_decompress_backend")
>>
>>> Signed-off-by: Gao Xiang <hsiangkao@...ux.alibaba.com>
>>> ---
>>>   fs/erofs/zdata.c | 8 ++++----
>>>   1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
>>> index ccf7c55d477f..08e982c77985 100644
>>> --- a/fs/erofs/zdata.c
>>> +++ b/fs/erofs/zdata.c
>>> @@ -1032,12 +1032,12 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
>>>       if (!be->decompressed_pages)
>>>           be->decompressed_pages =
>>> -            kvcalloc(be->nr_pages, sizeof(struct page *),
>>> -                 GFP_KERNEL | __GFP_NOFAIL);
>>> +            kcalloc(be->nr_pages, sizeof(struct page *),
>>> +                GFP_KERNEL | __GFP_NOFAIL);
>>>       if (!be->compressed_pages)
>>>           be->compressed_pages =
>>> -            kvcalloc(pclusterpages, sizeof(struct page *),
>>> -                 GFP_KERNEL | __GFP_NOFAIL);
>>> +            kcalloc(pclusterpages, sizeof(struct page *),
>>> +                GFP_KERNEL | __GFP_NOFAIL);
> 
> How about using kfree instead of kvfree for .decompressed_pages and
> .compressed_pages memory release? It's trivial though.

Yeah, thanks for catching! I will send v2 to fix these.

Thanks,
Gao Xiang

> 
> Anyway, feel free to add:
> 
> Reviewed-by: Chao Yu <chao@...nel.org>
> 
> Thanks,
> 
>>>       z_erofs_parse_out_bvecs(be);
>>>       err2 = z_erofs_parse_in_bvecs(be, &overlapped);