From: Li Nan <linan122@huawei.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@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.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;
 
 	if (bitmap->bp[page].hijacked ||
 	    bitmap->bp[page].map == NULL)
-- 
2.31.1

On Fri, May 5, 2023 at 6:24 PM <linan666@huaweicloud.com> wrote:
>
> From: Li Nan <linan122@huawei.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@huawei.com>
> Reviewed-by: Yu Kuai <yukuai3@huawei.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
of md_bitmap_checkpage(). (and fix the call site in md_bitmap_resize
for clustered md).

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

Thanks,
Song

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

在 2023/5/13 9:05, Song Liu 写道:
> On Fri, May 5, 2023 at 6:24 PM <linan666@huaweicloud.com> wrote:
>>
>> From: Li Nan <linan122@huawei.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@huawei.com>
>> Reviewed-by: Yu Kuai <yukuai3@huawei.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