linux-kernel - Re: [PATCH 1/3] md/raid10: fix slab-out-of-bounds in md_bitmap_get

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Message-ID: <39b4db2d-ae72-1006-fddf-244be5c83afb@huaweicloud.com>
Date:   Thu, 27 Apr 2023 18:23:54 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     linan666@...weicloud.com, song@...nel.org, neilb@...e.de,
        Rob.Becker@...erbed.com
Cc:     linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
        linan122@...wei.com, yi.zhang@...wei.com, houtao1@...wei.com,
        yangerkun@...wei.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH 1/3] md/raid10: fix slab-out-of-bounds in
 md_bitmap_get_counter

Hi,

在 2023/04/27 16:56, linan666@...weicloud.com 写道:
> 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>

This patch looks good to me, feel free to add：

Reviewed-by: Yu Kuai <yukuai3@...wei.com>

By the way, I think it's better for bitmap_store() to return error
number if bitmap doesn't exist or setting dirty bits failed.

Thnaks,
Kuai
> ---
>   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)
>