Re: [PATCH v2] fat: stop reading directory entries past the end-of-directory marker

[OGAWA Hirofumi]

Matteo Croce <technoboy85@xxxxxxxxx> writes:

> @@ -1310,12 +1333,15 @@ int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
>  	bh = prev = NULL;
>  	pos = 0;
>  	err = -ENOSPC;
> +	saw_eod = false;
>  	while (fat_get_entry(dir, &pos, &bh, &de) > -1) {
>  		/* check the maximum size of directory */
>  		if (pos >= FAT_MAX_DIR_SIZE)
>  			goto error;
>  
>  		if (IS_FREE(de->name)) {
> +			if (de->name[0] == 0)
> +				saw_eod = true;
>  			if (prev != bh) {
>  				get_bh(bh);
>  				bhs[nr_bhs] = prev = bh;
> @@ -1325,6 +1351,12 @@ int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
>  			if (free_slots == nr_slots)
>  				goto found;
>  		} else {
> +			if (saw_eod) {
> +				fat_msg_ratelimit(sb, KERN_WARNING,
> +					"allocated dir entry found after end-of-directory marker (i_pos %lld); please run fsck",
> +					MSDOS_I(dir)->i_pos);
> +				saw_eod = false;

Although this doesn't catch all cases, if it found the corruption, maybe
we should make FS read-only (fat_fs_error()), and return -EIO error? Is
there the reason to allow continue to write?

Thanks.

> +			}
>  			for (i = 0; i < nr_bhs; i++)
>  				brelse(bhs[i]);
>  			prev = NULL;

-- 
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>