Re: [PATCH] efi: fix panic in kdump kernel

[Johan Hovold]

On Fri, Mar 22, 2024 at 01:08:45AM +0000, Oleksandr Tymoshenko wrote:
> Check if get_next_variable() is actually valid pointer before
> calling it. In kdump kernel this method is set to NULL that causes
> panic during the kexec-ed kernel boot.
> 
> Tested with QEMU and OVMF firmware.

Sounds like you want a Fixes and CC stable tag here as well.

> Signed-off-by: Oleksandr Tymoshenko <ovt@xxxxxxxxxx>
> ---
>  drivers/firmware/efi/efi.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 8859fb0b006d..800b85807a02 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -203,6 +203,8 @@ static bool generic_ops_supported(void)
>  
>  	name_size = sizeof(name);
>  
> +	if (efi.get_next_variable == NULL)
> +		return false;

Please move this check above the name_size initialisation and make sure
you have a new line before and after.

I'd also suggest rewriting this as:

	if (!efi.get_next_variable)
		return false;

>  	status = efi.get_next_variable(&name_size, &name, &guid);
>  	if (status == EFI_UNSUPPORTED)
>  		return false;

Johan