From: Peter Jones <pjones@redhat.com>
Date: Mon, 2 Oct 2017 18:25:29 -0400
Subject: [PATCH 6/7] Make get_cert_list() not complain about cert lists that
 aren't present.
Origin: https://git.kernel.org/pub/scm/linux/kernel/git/jforbes/linux.git/commit/?id=0f4d5c7b49b45e7cf038bb769e33451b78a6445d

Signed-off-by: Peter Jones <pjones@redhat.com>
---
 certs/load_uefi.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

Index: linux/certs/load_uefi.c
===================================================================
--- linux.orig/certs/load_uefi.c
+++ linux/certs/load_uefi.c
@@ -35,8 +35,8 @@ static __init bool uefi_check_ignore_db(
 /*
  * Get a certificate list blob from the named EFI variable.
  */
-static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
-				  unsigned long *size)
+static __init int get_cert_list(efi_char16_t *name, efi_guid_t *guid,
+				unsigned long *size, void **cert_list)
 {
 	efi_status_t status;
 	unsigned long lsize = 4;
@@ -44,26 +44,33 @@ static __init void *get_cert_list(efi_ch
 	void *db;
 
 	status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb);
+	if (status == EFI_NOT_FOUND) {
+		*size = 0;
+		*cert_list = NULL;
+		return 0;
+	}
+
 	if (status != EFI_BUFFER_TOO_SMALL) {
 		pr_err("Couldn't get size: 0x%lx\n", status);
-		return NULL;
+		return efi_status_to_err(status);
 	}
 
 	db = kmalloc(lsize, GFP_KERNEL);
 	if (!db) {
 		pr_err("Couldn't allocate memory for uefi cert list\n");
-		return NULL;
+		return -ENOMEM;
 	}
 
 	status = efi.get_variable(name, guid, NULL, &lsize, db);
 	if (status != EFI_SUCCESS) {
 		kfree(db);
 		pr_err("Error reading db var: 0x%lx\n", status);
-		return NULL;
+		return efi_status_to_err(status);
 	}
 
 	*size = lsize;
-	return db;
+	*cert_list = db;
+	return 0;
 }
 
 /*
@@ -152,10 +159,10 @@ static int __init load_uefi_certs(void)
 	 * an error if we can't get them.
 	 */
 	if (!uefi_check_ignore_db()) {
-		db = get_cert_list(L"db", &secure_var, &dbsize);
-		if (!db) {
+		rc = get_cert_list(L"db", &secure_var, &dbsize, &db);
+		if (rc < 0) {
 			pr_err("MODSIGN: Couldn't get UEFI db list\n");
-		} else {
+		} else if (dbsize != 0) {
 			rc = parse_efi_signature_list("UEFI:db",
 						      db, dbsize, get_handler_for_db);
 			if (rc)
@@ -164,10 +171,10 @@ static int __init load_uefi_certs(void)
 		}
 	}
 
-	mok = get_cert_list(L"MokListRT", &mok_var, &moksize);
-	if (!mok) {
+	rc = get_cert_list(L"MokListRT", &mok_var, &moksize, &mok);
+	if (rc < 0) {
 		pr_info("MODSIGN: Couldn't get UEFI MokListRT\n");
-	} else {
+	} else if (moksize != 0) {
 		rc = parse_efi_signature_list("UEFI:MokListRT",
 					      mok, moksize, get_handler_for_db);
 		if (rc)
@@ -175,10 +182,10 @@ static int __init load_uefi_certs(void)
 		kfree(mok);
 	}
 
-	dbx = get_cert_list(L"dbx", &secure_var, &dbxsize);
-	if (!dbx) {
+	rc = get_cert_list(L"dbx", &secure_var, &dbxsize, &dbx);
+	if (rc < 0) {
 		pr_info("MODSIGN: Couldn't get UEFI dbx list\n");
-	} else {
+	} else if (dbxsize != 0) {
 		rc = parse_efi_signature_list("UEFI:dbx",
 					      dbx, dbxsize,
 					      get_handler_for_dbx);