From 493bd940e5c6e28e673034687de7adef9529efff Mon Sep 17 00:00:00 2001

From: Peter Jones <pjones@redhat.com>

Date: Sat, 10 Apr 2021 16:05:23 -0400

Subject: [PATCH 05/35] Don't call QueryVariableInfo() on EFI 1.10 machines

The EFI 1.10 spec (and presumably earlier revisions as well) didn't have

RT->QueryVariableInfo(), and on Chris Murphy's MacBookPro8,2 , that

memory appears to be initialized randomly.

This patch changes it to not call RT->QueryVariableInfo() if the

EFI_RUNTIME_SERVICES table's major revision is less than two, and

assumes our maximum variable size is 1024 in that case.

Signed-off-by: Peter Jones <pjones@redhat.com>

---

 mok.c | 23 ++++++++++++++++++-----

 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/mok.c b/mok.c

index 9b8fc2bc..beac0ff6 100644

--- a/mok.c

+++ b/mok.c

@@ -261,6 +261,9 @@ static const uint8_t null_sha256[32] = { 0, };

 typedef UINTN SIZE_T;

+#define EFI_MAJOR_VERSION(tablep) ((UINT16)((((tablep)->Hdr.Revision) >> 16) & 0xfffful))

+#define EFI_MINOR_VERSION(tablep) ((UINT16)(((tablep)->Hdr.Revision) & 0xfffful))

+

 static EFI_STATUS

 get_max_var_sz(UINT32 attrs, SIZE_T *max_var_szp)

 {

@@ -270,11 +273,21 @@ get_max_var_sz(UINT32 attrs, SIZE_T *max_var_szp)

 	uint64_t max_var_sz = 0;

 	*max_var_szp = 0;

-	efi_status = gRT->QueryVariableInfo(attrs, &max_storage_sz,

-					    &remaining_sz, &max_var_sz);

-	if (EFI_ERROR(efi_status)) {

-		perror(L"Could not get variable storage info: %r\n", efi_status);

-		return efi_status;

+	if (EFI_MAJOR_VERSION(gRT) < 2) {

+		dprint(L"EFI %d.%d; no RT->QueryVariableInfo().  Using 1024!\n",

+		       EFI_MAJOR_VERSION(gRT), EFI_MINOR_VERSION(gRT));

+		max_var_sz = remaining_sz = max_storage_sz = 1024;

+		efi_status = EFI_SUCCESS;

+	} else {

+		dprint(L"calling RT->QueryVariableInfo() at 0x%lx\n",

+		       gRT->QueryVariableInfo);

+		efi_status = gRT->QueryVariableInfo(attrs, &max_storage_sz,

+						    &remaining_sz, &max_var_sz);

+		if (EFI_ERROR(efi_status)) {

+			perror(L"Could not get variable storage info: %r\n",

+			       efi_status);

+			return efi_status;

+		}

 	}

 	/*

-- 

2.32.0