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boot: Drop use of UnpackDevicePath

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Device paths are a packed data structure and the UEFI spec is clear that
members may be misaligned.

In this case all accesses are aligned except for the signature. We can
simply memcpy it instead of making a whole (aligned) copy of the device
path.
This commit is contained in:
Jan Janssen 2022-05-29 10:33:42 +02:00
parent 79a2b916a0
commit b04f818417
1 changed files with 14 additions and 13 deletions
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27
src/boot/efi/disk.c
View file

@ -8,31 +8,32 @@
EFI_STATUS disk_get_part_uuid(EFI_HANDLE *handle, CHAR16 uuid[static 37]) {
EFI_STATUS err;
EFI_DEVICE_PATH *device_path;
_cleanup_freepool_ EFI_DEVICE_PATH *paths = NULL;
EFI_DEVICE_PATH *dp;
/* export the device path this image is started from */
if (!handle)
return EFI_NOT_FOUND;
err = BS->HandleProtocol(handle, &DevicePathProtocol, (void **) &device_path);
err = BS->HandleProtocol(handle, &DevicePathProtocol, (void **) &dp);
if (err != EFI_SUCCESS)
return err;
paths = UnpackDevicePath(device_path);
for (EFI_DEVICE_PATH *path = paths; !IsDevicePathEnd(path); path = NextDevicePathNode(path)) {
HARDDRIVE_DEVICE_PATH *drive;
if (DevicePathType(path) != MEDIA_DEVICE_PATH)
for (; !IsDevicePathEnd(dp); dp = NextDevicePathNode(dp)) {
if (DevicePathType(dp) != MEDIA_DEVICE_PATH)
continue;
if (DevicePathSubType(path) != MEDIA_HARDDRIVE_DP)
continue;
drive = (HARDDRIVE_DEVICE_PATH *)path;
if (drive->SignatureType != SIGNATURE_TYPE_GUID)
if (DevicePathSubType(dp) != MEDIA_HARDDRIVE_DP)
continue;
GuidToString(uuid, (EFI_GUID *)&drive->Signature);
HARDDRIVE_DEVICE_PATH *hd = (HARDDRIVE_DEVICE_PATH *) dp;
if (hd->SignatureType != SIGNATURE_TYPE_GUID)
continue;
/* Use memcpy in case the device path node is misaligned. */
EFI_GUID sig;
memcpy(&sig, hd->Signature, sizeof(hd->Signature));
GuidToString(uuid, &sig);
return EFI_SUCCESS;
}