4 files changed, 14 insertions, 10 deletions

diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c
index dcae482a9a17..e29560e6b40b 100644
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -175,7 +175,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	unsigned long initrd_addr;
 	u64 initrd_size = 0;
 	unsigned long fdt_addr = 0;  /* Original DTB */
-	u64 fdt_size = 0;  /* We don't get size from configuration table */
+	unsigned long fdt_size = 0;
 	char *cmdline_ptr = NULL;
 	int cmdline_size = 0;
 	unsigned long new_fdt_addr;
@@ -239,8 +239,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 	} else {
 		status = handle_cmdline_files(sys_table, image, cmdline_ptr,
 					      "dtb=",
-					      ~0UL, (unsigned long *)&fdt_addr,
-					      (unsigned long *)&fdt_size);
+					      ~0UL, &fdt_addr, &fdt_size);
 
 		if (status != EFI_SUCCESS) {
 			pr_efi_err(sys_table, "Failed to load device tree!\n");
@@ -252,7 +251,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
 		pr_efi(sys_table, "Using DTB from command line\n");
 	} else {
 		/* Look for a device tree configuration table entry. */
-		fdt_addr = (uintptr_t)get_fdt(sys_table);
+		fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
 		if (fdt_addr)
 			pr_efi(sys_table, "Using DTB from configuration table\n");
 	}
diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 2fe195002021..f07d4a67fa76 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -179,12 +179,12 @@ again:
 		start = desc->phys_addr;
 		end = start + desc->num_pages * (1UL << EFI_PAGE_SHIFT);
 
-		if ((start + size) > end || (start + size) > max)
-			continue;
-
-		if (end - size > max)
+		if (end > max)
 			end = max;
 
+		if ((start + size) > end)
+			continue;
+
 		if (round_down(end - size, align) < start)
 			continue;
 
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 47437b16b186..e334a01cf92f 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -41,7 +41,7 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
 					    unsigned long fdt_addr,
 					    unsigned long fdt_size);
 
-void *get_fdt(efi_system_table_t *sys_table);
+void *get_fdt(efi_system_table_t *sys_table, unsigned long *fdt_size);
 
 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 91da56c4fd54..ef5d764e2a27 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -323,7 +323,7 @@ fail:
 	return EFI_LOAD_ERROR;
 }
 
-void *get_fdt(efi_system_table_t *sys_table)
+void *get_fdt(efi_system_table_t *sys_table, unsigned long *fdt_size)
 {
 	efi_guid_t fdt_guid = DEVICE_TREE_GUID;
 	efi_config_table_t *tables;
@@ -336,6 +336,11 @@ void *get_fdt(efi_system_table_t *sys_table)
 	for (i = 0; i < sys_table->nr_tables; i++)
 		if (efi_guidcmp(tables[i].guid, fdt_guid) == 0) {
 			fdt = (void *) tables[i].table;
+			if (fdt_check_header(fdt) != 0) {
+				pr_efi_err(sys_table, "Invalid header detected on UEFI supplied FDT, ignoring ...\n");
+				return NULL;
+			}
+			*fdt_size = fdt_totalsize(fdt);
 			break;
 	 }