[PATCH 1/1] efi_loader: correct block IO alignment check

[Heinrich Schuchardt]

If the field Media->IoAlign of the EFI block IO protocol is zero, no
alignment is required. Our code required 4 GiB alignment in this case.

Don't check buffer alignment if Media->IoAlign == 0.

Fixes: f59f0825e8b9 ("efi_loader: parameter checks BLOCK_IO_PROTOCOL")
Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 lib/efi_loader/efi_disk.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
index c0804effde..d0aad0252a 100644
--- a/lib/efi_loader/efi_disk.c
+++ b/lib/efi_loader/efi_disk.c
@@ -142,8 +142,9 @@ static efi_status_t EFIAPI efi_disk_read_blocks(struct efi_block_io *this,
 		return EFI_MEDIA_CHANGED;
 	if (!this->media->media_present)
 		return EFI_NO_MEDIA;
-	/* media->io_align is a power of 2 */
-	if ((uintptr_t)buffer & (this->media->io_align - 1))
+	/* media->io_align is a power of 2 or 0 */
+	if (this->media->io_align &&
+	    (uintptr_t)buffer & (this->media->io_align - 1))
 		return EFI_INVALID_PARAMETER;
 	if (lba * this->media->block_size + buffer_size >
 	    this->media->last_block * this->media->block_size)
@@ -209,8 +210,9 @@ static efi_status_t EFIAPI efi_disk_write_blocks(struct efi_block_io *this,
 		return EFI_MEDIA_CHANGED;
 	if (!this->media->media_present)
 		return EFI_NO_MEDIA;
-	/* media->io_align is a power of 2 */
-	if ((uintptr_t)buffer & (this->media->io_align - 1))
+	/* media->io_align is a power of 2 or 0 */
+	if (this->media->io_align &&
+	    (uintptr_t)buffer & (this->media->io_align - 1))
 		return EFI_INVALID_PARAMETER;
 	if (lba * this->media->block_size + buffer_size >
 	    this->media->last_block * this->media->block_size)
--
2.29.2