linux-ext4 - Re: [PATCH v2] ext4: check if offset+length is within valid fallocate

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Date:   Thu, 28 Apr 2022 16:02:09 +0200
From:   Jan Kara <jack@...e.cz>
To:     Tadeusz Struk <tadeusz.struk@...aro.org>
Cc:     syzbot+fcc629d1a1ae8d3fe8a5@...kaller.appspotmail.com,
        syzkaller-bugs@...glegroups.com, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org, tytso@....edu
Subject: Re: [PATCH v2] ext4: check if offset+length is within valid fallocate

On Tue 15-03-22 14:38:57, Tadeusz Struk wrote:
> #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

Did this fix fall through the cracks? Tadeusz, can you do a proper patch
submission with your Signed-off-by etc.? Thanks!

								Honza

> 
> ==============================================
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 01c9e4f743ba..355384007d11 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3924,7 +3924,8 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
>  	struct super_block *sb = inode->i_sb;
>  	ext4_lblk_t first_block, stop_block;
>  	struct address_space *mapping = inode->i_mapping;
> -	loff_t first_block_offset, last_block_offset;
> +	loff_t first_block_offset, last_block_offset, max_length;
> +	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
>  	handle_t *handle;
>  	unsigned int credits;
>  	int ret = 0, ret2 = 0;
> @@ -3967,6 +3968,16 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
>  		   offset;
>  	}
>  
> +	/*
> +	 * For punch hole the length + offset needs to be at least within
> +	 * one block before last
> +	 */
> +	max_length = sbi->s_bitmap_maxbytes - inode->i_sb->s_blocksize;
> +	if (offset + length >= max_length) {
> +		ret = -ENOSPC;
> +		goto out_mutex;
> +	}
> +
>  	if (offset & (sb->s_blocksize - 1) ||
>  	    (offset + length) & (sb->s_blocksize - 1)) {
>  		/*
> -- 
> 2.35.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR