diff mbox series

[5.10,144/157] efivars: respect EFI_UNSUPPORTED return from firmware

Message ID 20210322121938.315527706@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman March 22, 2021, 12:28 p.m. UTC 
From: Shawn Guo <shawn.guo@linaro.org>


commit 483028edacab374060d93955382b4865a9e07cba upstream.

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>

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/firmware/efi/vars.c |    4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -485,6 +485,10 @@  int efivar_init(int (*func)(efi_char16_t
 			}
 
 			break;
+		case EFI_UNSUPPORTED:
+			err = -EOPNOTSUPP;
+			status = EFI_NOT_FOUND;
+			break;
 		case EFI_NOT_FOUND:
 			break;
 		default: