linux-ext4 - Re: [PATCHv1 9/9] ext4: Add extra check in ext4_mb_mark_bb() to prevent against possible corruption

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Date:   Mon, 7 Feb 2022 17:45:41 +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: [PATCHv1 9/9] ext4: Add extra check in ext4_mb_mark_bb() to
 prevent against possible corruption

On Sat 05-02-22 19:39:58, 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.
> 
> Suggested-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Ritesh Harjani <riteshh@...ux.ibm.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext4/mballoc.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 9f2b3a057918..75c20a10529a 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -3918,6 +3918,14 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
>  			EXT4_BLOCKS_PER_GROUP(sb) - EXT4_C2B(sbi, blkoff));
>  		clen = EXT4_NUM_B2C(sbi, thisgrp_len);
>  
> +		if (!ext4_sb_block_valid(sb, NULL, block, thisgrp_len)) {
> +			ext4_error(sb, "Marking blocks in system zone - "
> +				   "Block = %llu, len = %u",
> +				   block, thisgrp_len);
> +			bitmap_bh = NULL;
> +			break;
> +		}
> +
>  		bitmap_bh = ext4_read_block_bitmap(sb, group);
>  		if (IS_ERR(bitmap_bh)) {
>  			err = PTR_ERR(bitmap_bh);
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR