From 483028edacab374060d93955382b4865a9e07cba Mon Sep 17 00:00:00 2001 From: Shawn Guo Date: Wed, 17 Mar 2021 14:36:06 +0800 Subject: [PATCH] efivars: respect EFI_UNSUPPORTED return from firmware As per UEFI spec 2.8B section 8.2, EFI_UNSUPPORTED may be returned by EFI variable runtime services if no variable storage is supported by firmware. In this case, there is no point for kernel to continue efivars initialization. That said, efivar_init() should fail by returning an error code, so that efivarfs will not be mounted on /sys/firmware/efi/efivars at all. Otherwise, user space like efibootmgr will be confused by the EFIVARFS_MAGIC seen there, while EFI variable calls cannot be made successfully. Cc: # v5.10+ Signed-off-by: Shawn Guo Acked-by: Ard Biesheuvel Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/vars.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c index 41c1d00bf933..abdc8a6a3963 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -484,6 +484,10 @@ int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *), } } + break; + case EFI_UNSUPPORTED: + err = -EOPNOTSUPP; + status = EFI_NOT_FOUND; break; case EFI_NOT_FOUND: break;