Re: [PATCH] x86, kdump: Fix efi=noruntime NULL pointer dereference

[Mike Galbraith]

On Fri, 2018-08-10 at 16:45 +0800, Dave Young wrote:
> 
> BTW, this patch only fix the kexec load phase problem,  even if kexec
> load successfully with the fix, the 2nd kernel can not boot because efi
> memmap info is not correct and usable.

Hm.  I didn't do anything else with kexec, but did crashdump my box
both w/wo efi=noruntime.

> So we should go with some fix similar to below, and do the cleanup we
> mentioned with a separate patch later.

Ah, you mean the one I had _just_ built when I saw this :)

> Also user space kexec-tools need a similar patch to error out in case
> no runtime maps.  It would be good to fix both userspace and kernel
> load.
> 
> diff --git a/arch/x86/kernel/kexec-bzimage64.c 
> b/arch/x86/kernel/kexec-bzimage64.c
> index 7326078eaa7a..e34ba2f53cfb 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -123,7 +123,7 @@ static int setup_efi_info_memmap(struct boot_params 
> *params,
>       struct efi_info *ei = &params->efi_info;
>  
>       if (!efi_map_sz)
> -             return 0;
> +             return -EINVAL;
>  
>       efi_runtime_map_copy(efi_map, efi_map_sz);
>  
> @@ -166,9 +166,10 @@ setup_efi_state(struct boot_params *params, unsigned 
> long params_load_addr,
>  {
>       struct efi_info *current_ei = &boot_params.efi_info;
>       struct efi_info *ei = &params->efi_info;
> +     int ret;
>  
>       if (!current_ei->efi_memmap_size)
> -             return 0;
> +             return -EINVAL;
>  
>       /*
>        * If 1:1 mapping is not enabled, second kernel can not setup EFI
> @@ -176,8 +177,8 @@ setup_efi_state(struct boot_params *params, unsigned long 
> params_load_addr,
>        * acpi_rsdp=<addr> on kernel command line to make second kernel boot
>        * without efi.
>        */
> -     if (efi_enabled(EFI_OLD_MEMMAP))
> -             return 0;
> +     if (efi_enabled(EFI_OLD_MEMMAP) || !efi_enabled(EFI_RUNTIME_SERVICES))
> +             return -ENODEV;
>  
>       ei->efi_loader_signature = current_ei->efi_loader_signature;
>       ei->efi_systab = current_ei->efi_systab;
> @@ -186,8 +187,10 @@ setup_efi_state(struct boot_params *params, unsigned 
> long params_load_addr,
>       ei->efi_memdesc_version = current_ei->efi_memdesc_version;
>       ei->efi_memdesc_size = efi_get_runtime_map_desc_size();
>  
> -     setup_efi_info_memmap(params, params_load_addr, efi_map_offset,
> +     ret = setup_efi_info_memmap(params, params_load_addr, efi_map_offset,
>                             efi_map_sz);
> +     if (ret)
> +             return ret;
>       prepare_add_efi_setup_data(params, params_load_addr,
>                                  efi_setup_data_offset);
>       return 0;
> @@ -250,8 +253,10 @@ setup_boot_parameters(struct kimage *image, struct 
> boot_params *params,
>  
>  #ifdef CONFIG_EFI
>       /* Setup EFI state */
> -     setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
> +     ret = setup_efi_state(params, params_load_addr, efi_map_offset, 
> efi_map_sz,
>                       efi_setup_data_offset);
> +     if (ret)
> +             return ret;
>  #endif
>  
>       /* Setup EDD info */