Re: [PATCH v3 3/3] hw/smbios: add assertion to ensure handles of tables 19 and 32 do not collide

[Igor Mammedov]

On Mon, 14 Feb 2022 19:42:36 +0530
Ani Sinha <ani@anisinha.ca> wrote:

> Since change b3cddba9c14b034 ("hw/smbios: fix table memory corruption with 
> large memory vms")
> we reserve additional space between handle numbers of tables 17 and 19 for
> large VMs. This may cause table 19 to collide with table 32 in their handle
> numbers for those large VMs. This change adds an assertion to ensure numbers
> do not collide. If they do, qemu crashes with useful debug information for
> taking additional steps.
> 
> Signed-off-by: Ani Sinha <ani@anisinha.ca>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  hw/smbios/smbios.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> changelog:
> v3: reworded the commit log and comment in code.
> 
> diff --git a/hw/smbios/smbios.c b/hw/smbios/smbios.c
> index 44c53797a4..1f8d5c252f 100644
> --- a/hw/smbios/smbios.c
> +++ b/hw/smbios/smbios.c
> @@ -1048,6 +1048,12 @@ void smbios_get_tables(MachineState *ms,
>                                         mem_array[i].length);
>          }
>  
> +        /*
> +         * make sure 16 bit handle numbers in the headers of tables 19
> +         * and 32 do not overlap.
> +         */
> +        assert((mem_array_size + offset) < (T32_BASE - T19_BASE));
> +
>          smbios_build_type_32_table();
>          smbios_build_type_38_table();
>          smbios_build_type_41_table(errp);