Re: [PATCH] test: lib/uuid: Fix endianness for dynamic GUIDs

On 8/27/26 15:00, Alexey Charkov wrote:
> If LIB_UUID is enabled on a big-endian board, such as when it is pulled
> in by EFI_PARTITION, its tests will fail due to the dynamic capsule GUIDs
> computed by lib_test_dynamic_uuid() using native endianness for the UTF-16
> image name, instead of little-endian:
> 
>    malta # ut lib lib_test_dynamic_uuid
>    Test: dynamic_uuid: uuid.c
>    test/lib/uuid.c:114, lib_test_dynamic_uuid_case(): expected_uuid = uuid_str: Expected "985f2937-7c2e-5e9a-8a5e-8e063312964b", got "829f5cb0-1a07-5718-8774-4514bda82c39"
>    Test 'dynamic_uuid' failed 1 times
>    Tests run: 1, 2 ms, average: 2 ms, failures: 1
>    exit not allowed from main input shell.
>    malta #
> 
> Add explicit endianness conversion to the test and to other similar
> callers of gen_v5_guid() to make sure they work uniformly regardless of
> the host or target endianness.
> 
> Signed-off-by: Alexey Charkov <[email protected]>

Thank you for reporting that the test fails on big endian systems.

In lib_test_dynamic_uuid() we define define dynamic_uuid_test_data 
test_data[].images as u16 string. On a big endian system the characters 
of the string will not be stored in the same sequence as on a low endian 
system so the UUID generated in gen_v5_guid() is expected to be different.

test_data[].images should contain unique sequences of bytes.

The relevant code was introduced with
26e16a850e64 ("test: lib/uuid: add unit tests for dynamic UUIDs")

With that I don't think that the EFI changes are needed. Anyway UEFI is 
little endian only.

Best regards

Heinrich

> ---
> This was uncovered [1] while adding tests for GPT partition labels on big
> endian boards, which pulls in PARTITION_UUIDS, which in turn pulls in
> LIB_UUID and its tests. Turns out no BE board in CI ever enabled LIB_UUID,
> so this went unnoticed to date.
> 
> The immediate users of this code other than the test suite are EFI capsule
> updates, which is unlikely to be relevant for anything big endian (given
> that UEFI is little endian), but the test suite itself seems to be a good
> reason to get this fixed.
> 
> No functional change on little endian either way.
> 
> [1] https://git.u-boot-project.org/u-boot/contributors/alchark/u-boot/-/pipelines/1101
> ---
>   include/u-boot/uuid.h         |  5 +++++
>   lib/efi_loader/efi_firmware.c | 19 ++++++++++++++++++-
>   test/lib/uuid.c               | 15 ++++++++++++++-
>   tools/mkeficapsule.c          |  3 ++-
>   4 files changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/include/u-boot/uuid.h b/include/u-boot/uuid.h
> index 7f8414dc906c..acdf3a85a6cb 100644
> --- a/include/u-boot/uuid.h
> +++ b/include/u-boot/uuid.h
> @@ -149,6 +149,11 @@ struct efi_guid;
>   /**
>    * gen_v5_guid() - generate little endian v5 GUID from namespace and other seed data.
>    *
> + * The seed data is hashed as raw bytes, so any of it that is not a byte string
> + * has to be supplied in a fixed byte order for the result to be reproducible.
> + * UTF-16 seed data, such as a firmware image name, must therefore be passed
> + * little-endian, which is the byte order the UEFI specification uses for it.
> + *
>    * @namespace:   pointer to UUID namespace salt
>    * @guid:        pointer to allocated GUID output
>    * @...:         NULL terminated list of seed data as pairs of pointers
> diff --git a/lib/efi_loader/efi_firmware.c b/lib/efi_loader/efi_firmware.c
> index b41969c70fde..7f3b2da3ef89 100644
> --- a/lib/efi_loader/efi_firmware.c
> +++ b/lib/efi_loader/efi_firmware.c
> @@ -279,15 +279,32 @@ static efi_status_t efi_gen_capsule_guids(void)
>   	}
>   
>   	for (i = 0; i < update_info.num_images; i++) {
> +		size_t len, j;
> +		u16 *name_le;
> +
>   		if (!fw_array[i].fw_name) {
>   			log_err("fw_name is not defined. Not generating capsule GUIDs\n");
>   			return EFI_INVALID_PARAMETER;
>   		}
> +
> +		/*
> +		 * The name is hashed as UTF-16LE, so that a big-endian board
> +		 * arrives at the same GUID as mkeficapsule running on a
> +		 * little-endian build host.
> +		 */
> +		len = u16_strlen(fw_array[i].fw_name);
> +		name_le = calloc(len, sizeof(*name_le));
> +		if (!name_le)
> +			return EFI_OUT_OF_RESOURCES;
> +		for (j = 0; j < len; j++)
> +			name_le[j] = cpu_to_le16(fw_array[i].fw_name[j]);
> +
>   		gen_v5_guid(&namespace,
>   			    &fw_array[i].image_type_id,
>   			    compatible, strlen(compatible),
> -			    fw_array[i].fw_name, u16_strlen(fw_array[i].fw_name) * sizeof(uint16_t),
> +			    name_le, len * sizeof(*name_le),
>   			    NULL);
> +		free(name_le);
>   
>   		log_debug("Image %ls UUID %pUl\n", fw_array[i].fw_name,
>   			  &fw_array[i].image_type_id);
> diff --git a/test/lib/uuid.c b/test/lib/uuid.c
> index d00e9563a472..1c66021af3ed 100644
> --- a/test/lib/uuid.c
> +++ b/test/lib/uuid.c
> @@ -10,6 +10,7 @@
>   
>   #include <charset.h>
>   #include <u-boot/uuid.h>
> +#include <asm/byteorder.h>
>   #include <test/lib.h>
>   #include <test/test.h>
>   #include <test/ut.h>
> @@ -102,12 +103,24 @@ static int lib_test_dynamic_uuid_case(struct unit_test_state *uts,
>   	for (j = 0; data->images[j]; j++) {
>   		const char *expected_uuid = data->expected_uuids[j];
>   		const u16 *image = data->images[j];
> +		u16 image_le[64];
>   		efi_guid_t uuid;
>   		char uuid_str[37];
> +		size_t len, k;
> +
> +		/*
> +		 * u"..." is native-endian, but the name is hashed as UTF-16LE
> +		 * so that the GUID does not depend on the endianness of the
> +		 * board or of the host running mkeficapsule.
> +		 */
> +		len = u16_strlen(image);
> +		ut_assert(len <= ARRAY_SIZE(image_le));
> +		for (k = 0; k < len; k++)
> +			image_le[k] = cpu_to_le16(image[k]);
>   
>   		gen_v5_guid(&namespace, &uuid,
>   			    data->compatible, strlen(data->compatible),
> -			    image, u16_strlen(image) * sizeof(uint16_t),
> +			    image_le, len * sizeof(*image_le),
>   			    NULL);
>   		uuid_bin_to_str((unsigned char *)&uuid, uuid_str, UUID_STR_FORMAT_GUID);
>   
> diff --git a/tools/mkeficapsule.c b/tools/mkeficapsule.c
> index ec640c57e8a5..55a58f07d56e 100644
> --- a/tools/mkeficapsule.c
> +++ b/tools/mkeficapsule.c
> @@ -1004,8 +1004,9 @@ static int genguid(int argc, char **argv)
>   			return -1;
>   		}
>   
> +		/* The name is hashed as UTF-16LE, whatever this host is */
>   		for (int i = 0; i < namelen; i++)
> -			fw_image[i] = (uint16_t)argv[idx][i];
> +			fw_image[i] = cpu_to_le16((uint16_t)argv[idx][i]);
>   
>   		gen_v5_guid((struct uuid *)&namespace, &image_type_id,
>   			    compatible, strlen(compatible),
> 
> ---
> base-commit: 964ad5b5c91b7be56e443e899d7f873e6aa8c9fc
> change-id: 20260827-uuid-be-56657e7aa80e
> 
> Best regards,
> --
> Alexey Charkov <[email protected]>
>