Re: [PATCH 1/3] nfit: in acpi_nfit_init, break on a 0-length table

[Jeff Moyer <jmoyer@redhat.com>]

Vishal Verma <vishal.l.verma@intel.com> writes:

> If acpi_nfit_init is called (such as from nfit_test), with an nfit table
> that has more memory allocated than it needs (and a similarly large
> 'size' field, add_tables would happily keep adding null SPA Range tables
> filling up all available memory.
>
> Make it friendlier by breaking out if a 0-length header is found in any
> of the tables.

Shouldn't that at least spew a warning?  Or does the spec allow for
zero-length tables?

-Jeff

>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: <linux-acpi@vger.kernel.org>
> Cc: <linux-nvdimm@lists.01.org>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
>  drivers/acpi/nfit.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/acpi/nfit.c b/drivers/acpi/nfit.c
> index c1b8d03..ed599d1 100644
> --- a/drivers/acpi/nfit.c
> +++ b/drivers/acpi/nfit.c
> @@ -335,6 +335,9 @@ static void *add_table(struct acpi_nfit_desc *acpi_desc, void *table,
>  		return NULL;
>  
>  	hdr = table;
> +	if (!hdr->length)
> +		return NULL;
> +
>  	switch (hdr->type) {
>  	case ACPI_NFIT_TYPE_SYSTEM_ADDRESS:
>  		if (!add_spa(acpi_desc, table))