Re: [PULL 22/33] spapr: Implement Open Firmware client interface

[Peter Maydell]

On Fri, 9 Jul 2021 at 06:17, David Gibson <david@gibson.dropbear.id.au> wrote:
>
> From: Alexey Kardashevskiy <aik@ozlabs.ru>
>
> The PAPR platform describes an OS environment that's presented by
> a combination of a hypervisor and firmware. The features it specifies
> require collaboration between the firmware and the hypervisor.

Hi; Coverity reports issues in this code:


> +static uint32_t vof_package_to_path(const void *fdt, uint32_t phandle,
> +                                    uint32_t buf, uint32_t len)
> +{
> +    uint32_t ret = -1;

Here we declare 'ret' as an unsigned type...

> +    char tmp[VOF_MAX_PATH] = "";
> +
> +    ret = phandle_to_path(fdt, phandle, tmp, sizeof(tmp));
> +    if (ret > 0) {

...so this is doing an unsigned comparison, which means that
the negative values returned from phandle_to_path() (whose return
type is 'int') will not be detected (viewed as unsigned values
they will all be positive and >2GB).

> +        if (VOF_MEM_WRITE(buf, tmp, ret) != MEMTX_OK) {

This then means that we will attempt to write >2GB of data here...

> +            ret = -1;
> +        }
> +    }
> +
> +    trace_vof_package_to_path(phandle, tmp, ret);
> +
> +    return ret;
> +}
> +
> +static uint32_t vof_instance_to_path(void *fdt, Vof *vof, uint32_t ihandle,
> +                                     uint32_t buf, uint32_t len)
> +{
> +    uint32_t ret = -1;
> +    uint32_t phandle = vof_instance_to_package(vof, ihandle);
> +    char tmp[VOF_MAX_PATH] = "";
> +
> +    if (phandle != -1) {
> +        ret = phandle_to_path(fdt, phandle, tmp, sizeof(tmp));
> +        if (ret > 0) {

This function has the same problem.

> +            if (VOF_MEM_WRITE(buf, tmp, ret) != MEMTX_OK) {
> +                ret = -1;
> +            }
> +        }
> +    }
> +    trace_vof_instance_to_path(ihandle, phandle, tmp, ret);
> +
> +    return ret;
> +}

thanks
-- PMM