linux-kernel - Re: [PATCH v2 1/4] md/raid10: fix slab-out-of-bounds in md_bitmap_get

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Message-ID: <863a4b6e-ff85-2d82-cf8b-bec87e0f5468@huaweicloud.com>
Date:   Sun, 14 May 2023 19:15:43 +0800
From:   Li Nan <linan666@...weicloud.com>
To:     Song Liu <song@...nel.org>, linan666@...weicloud.com
Cc:     neilb@...e.de, linux-raid@...r.kernel.org,
        linux-kernel@...r.kernel.org, yukuai3@...wei.com,
        yi.zhang@...wei.com, houtao1@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH v2 1/4] md/raid10: fix slab-out-of-bounds in
 md_bitmap_get_counter



在 2023/5/13 9:05, Song Liu 写道:
> On Fri, May 5, 2023 at 6:24 PM <linan666@...weicloud.com> wrote:
>>
>> From: Li Nan <linan122@...wei.com>
>>
>> If we write a large number to md/bitmap_set_bits, md_bitmap_checkpage()
>> will return -EINVAL because "page >= bitmap->pages", but the return value
>> was not checked immediately in md_bitmap_get_counter() in order to set
>> *blocks value and slab-out-of-bounds occurs.
>>
>> Return directly if err is -EINVAL.
>>
>> Fixes: ef4256733506 ("md/bitmap: optimise scanning of empty bitmaps.")
>> Signed-off-by: Li Nan <linan122@...wei.com>
>> Reviewed-by: Yu Kuai <yukuai3@...wei.com>
>> ---
>>   drivers/md/md-bitmap.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
>> index 920bb68156d2..0b41ef422da7 100644
>> --- a/drivers/md/md-bitmap.c
>> +++ b/drivers/md/md-bitmap.c
>> @@ -1388,6 +1388,8 @@ __acquires(bitmap->lock)
>>          int err;
>>
>>          err = md_bitmap_checkpage(bitmap, page, create, 0);
>> +       if (err == -EINVAL)
>> +               return NULL;
> 
> This logic is error prone. Since we are on it, let's fix it better.
> Specifically, we can move "page >= bitmap->pages" check out

I will check out it in v3.

> of md_bitmap_checkpage(). (and fix the call site in md_bitmap_resize
> for clustered md).
> 

In md_bitmap_resize(), incoming parameters "page < bitmap->counts.page" 
and do not have this problem.


> Also, could you please add a mdadm test for this issue?
> 

It's my pleasure.

> Thanks,
> Song
> 
>>
>>          if (bitmap->bp[page].hijacked ||
>>              bitmap->bp[page].map == NULL)
>> --
>> 2.31.1
>>
> .

Thanks for your suggesion.

-- 
Thanks,
Nan