[PATCH 1/1] efi_loader: check device path is not installed twice

[Heinrich Schuchardt]

Prior to corrective patches for virtio and SATA devices the same device
path was installed on two different handles. This is not allowable.
With this patch we will throw an error if this condition occurs for
block devices.

Update a comment for the installation of the simple file system
protocol.

Reported-by: Ard Biesheuvel <ardb at kernel.org>
Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 lib/efi_loader/efi_disk.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
index 0582e02158..a04e23feb6 100644
--- a/lib/efi_loader/efi_disk.c
+++ b/lib/efi_loader/efi_disk.c
@@ -356,6 +356,7 @@ static efi_status_t efi_disk_add_dev(
 				struct efi_disk_obj **disk)
 {
 	struct efi_disk_obj *diskobj;
+	struct efi_object *handle;
 	efi_status_t ret;

 	/* Don't add empty devices */
@@ -379,15 +380,25 @@ static efi_status_t efi_disk_add_dev(
 		diskobj->dp = efi_dp_from_part(desc, part);
 	}
 	diskobj->part = part;
-	ret = efi_add_protocol(&diskobj->header, &efi_block_io_guid,
-			       &diskobj->ops);
-	if (ret != EFI_SUCCESS)
-		return ret;
-	ret = efi_add_protocol(&diskobj->header, &efi_guid_device_path,
-			       diskobj->dp);
+
+	/*
+	 * Install the device path and the block IO protocol.
+	 *
+	 * InstallMultipleProtocolInterfaces() checks if the device path is
+	 * already installed on an other handle and returns EFI_ALREADY_STARTED
+	 * in this case.
+	 */
+	handle = &diskobj->header;
+	ret = EFI_CALL(efi_install_multiple_protocol_interfaces(
+			&handle, &efi_guid_device_path, diskobj->dp,
+			&efi_block_io_guid, &diskobj->ops, NULL));
 	if (ret != EFI_SUCCESS)
 		return ret;
-	/* partitions or whole disk without partitions */
+
+	/*
+	 * On partitions or whole disks without partitions install the
+	 * simple file system protocol if a file system is available.
+	 */
 	if ((part || desc->part_type == PART_TYPE_UNKNOWN) &&
 	    efi_fs_exists(desc, part)) {
 		diskobj->volume = efi_simple_file_system(desc, part,
--
2.26.2