The following commit has been merged into the efi/urgent branch of tip:

Commit-ID: 483028edacab374060d93955382b4865a9e07cba Gitweb: https://git.kernel.org/tip/483028edacab374060d93955382b4865a9e07cba Author: Shawn Guo shawn.guo@linaro.org AuthorDate: Wed, 17 Mar 2021 14:36:06 +08:00 Committer: Ard Biesheuvel ardb@kernel.org CommitterDate: Wed, 17 Mar 2021 09:40:24 +01:00

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: stable@vger.kernel.org # v5.10+ Signed-off-by: Shawn Guo shawn.guo@linaro.org Acked-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Ard Biesheuvel ardb@kernel.org --- 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 41c1d00..abdc8a6 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -485,6 +485,10 @@ 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; default: