Re: [PATCH] efi_driver: fix a wrong cast

[Heinrich Schuchardt]

On 9/27/21 6:30 AM, AKASHI Takahiro wrote:

struct efi_driver_binding_protocol, i.e. bp, is not the first element
in struct efi_driver_binding_extended_protocol.
So the casting:
        struct efi_driver_binding_extended_protocol *bp =
                (struct efi_driver_binding_extended_protocol *)this;
is simply wrong.

The definition in include/efi_driver.h is:

/*
 * This structure adds internal fields to the driver binding protocol.
 */
struct efi_driver_binding_extended_protocol {
        struct efi_driver_binding_protocol bp;
        const struct efi_driver_ops *ops;
};

Why do you claim "bp is not the first element"?

The whole efi_driver code relies on the fact that the
efi_driver_binding_extended_protocol can be interpreted as
efi_driver_binding_protocol.

Best regards

Heinrich

Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org>
---
  lib/efi_driver/efi_uclass.c | 14 +++++++-------
  1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/lib/efi_driver/efi_uclass.c b/lib/efi_driver/efi_uclass.c
index 382c2b477f4d..9e784f9c237f 100644
--- a/lib/efi_driver/efi_uclass.c
+++ b/lib/efi_driver/efi_uclass.c
@@ -65,8 +65,8 @@ static efi_status_t EFIAPI efi_uc_supported(
  {
        efi_status_t r, ret;
        void *interface;
-       struct efi_driver_binding_extended_protocol *bp =
-                       (struct efi_driver_binding_extended_protocol *)this;
+       struct efi_driver_binding_extended_protocol *bp = container_of(this,
+                       struct efi_driver_binding_extended_protocol, bp);

        EFI_ENTRY("%p, %p, %ls", this, controller_handle,
                  efi_dp_str(remaining_device_path));
@@ -113,8 +113,8 @@ static efi_status_t EFIAPI efi_uc_start(
  {
        efi_status_t r, ret;
        void *interface = NULL;
-       struct efi_driver_binding_extended_protocol *bp =
-                       (struct efi_driver_binding_extended_protocol *)this;
+       struct efi_driver_binding_extended_protocol *bp = container_of(this,
+                       struct efi_driver_binding_extended_protocol, bp);

        EFI_ENTRY("%p, %p, %ls", this, controller_handle,
                  efi_dp_str(remaining_device_path));
@@ -201,8 +201,8 @@ static efi_status_t EFIAPI efi_uc_stop(
        efi_status_t ret;
        efi_uintn_t count;
        struct efi_open_protocol_info_entry *entry_buffer;
-       struct efi_driver_binding_extended_protocol *bp =
-                       (struct efi_driver_binding_extended_protocol *)this;
+       struct efi_driver_binding_extended_protocol *bp = container_of(this,
+                       struct efi_driver_binding_extended_protocol, bp);

        EFI_ENTRY("%p, %p, %zu, %p", this, controller_handle,
                  number_of_children, child_handle_buffer);
@@ -283,7 +283,7 @@ static efi_status_t efi_add_driver(struct driver *drv)
        }
        bp->bp.image_handle = bp->bp.driver_binding_handle;
        ret = efi_add_protocol(bp->bp.driver_binding_handle,
-                              &efi_guid_driver_binding_protocol, bp);
+                              &efi_guid_driver_binding_protocol, &bp->bp);
        if (ret != EFI_SUCCESS) {
                efi_delete_handle(bp->bp.driver_binding_handle);
                free(bp);