linux-ext4 - Re: [RFC 6/6] ext4: Add extra check in ext4_mb_mark_bb() to prevent against possible corruption

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Message-ID: <20220201114719.dzyeitz26kpde5zf@quack3.lan>
Date:   Tue, 1 Feb 2022 12:47:19 +0100
From:   Jan Kara <jack@...e.cz>
To:     Ritesh Harjani <riteshh@...ux.ibm.com>
Cc:     linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.cz>,
        Harshad Shirwadkar <harshadshirwadkar@...il.com>
Subject: Re: [RFC 6/6] ext4: Add extra check in ext4_mb_mark_bb() to prevent
 against possible corruption

On Mon 31-01-22 20:46:55, Ritesh Harjani wrote:
> This patch adds an extra checks in ext4_mb_mark_bb() function
> to make sure we mark & report error if we were to mark/clear any
> of the critical FS metadata specific bitmaps (&bail out) to prevent
> from any accidental corruption.
> 
> Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>

Again please rather use ext4_inode_block_valid() here. All the callers of
ext4_mb_mark_bb() have the information available.

								Honza

> ---
>  fs/ext4/mballoc.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 5f20e355d08c..c94888534caa 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -3920,6 +3920,13 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
>  		len -= overflow;
>  	}
>  
> +	if (!ext4_group_block_valid(sb, group, block, len)) {
> +		ext4_error(sb, "Marking blocks in system zone - "
> +			   "Block = %llu, len = %d", block, len);
> +		bitmap_bh = NULL;
> +		goto out_err;
> +	}
> +
>  	clen = EXT4_NUM_B2C(sbi, len);
>  
>  	bitmap_bh = ext4_read_block_bitmap(sb, group);
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR