From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Leif Lindholm <leif.lindholm@linaro.org>

Date: Sat, 27 Feb 2016 13:44:59 +0100

Subject: [PATCH] efidisk: Respect block_io_protocol buffer alignment

Returned from the OpenProtocol operation, the grub_efi_block_io_media

structure contains the io_align field, specifying the minimum alignment

required for buffers used in any data transfers with the device.

Make grub_efidisk_readwrite() allocate a temporary buffer, aligned to

this boundary, if the buffer passed to it does not already meet the

requirements.

Also sanity check the io_align field in grub_efidisk_open() for

power-of-two-ness and bail if invalid.

Cherry-picked-from: 51f375d688529b7c1819ba40188ee52b9333887c

Resolves: rhbz#1300009

---

 grub-core/disk/efi/efidisk.c | 48 +++++++++++++++++++++++++++++++++++++-------

 1 file changed, 41 insertions(+), 7 deletions(-)

diff --git a/grub-core/disk/efi/efidisk.c b/grub-core/disk/efi/efidisk.c

index 845c66fa9ab..f04f20b84ff 100644

--- a/grub-core/disk/efi/efidisk.c

+++ b/grub-core/disk/efi/efidisk.c

@@ -487,8 +487,15 @@ grub_efidisk_open (const char *name, struct grub_disk *disk)

   m = d->block_io->media;

   /* FIXME: Probably it is better to store the block size in the disk,

      and total sectors should be replaced with total blocks.  */

-  grub_dprintf ("efidisk", "m = %p, last block = %llx, block size = %x\n",

-		m, (unsigned long long) m->last_block, m->block_size);

+  grub_dprintf ("efidisk",

+		"m = %p, last block = %llx, block size = %x, io align = %x\n",

+		m, (unsigned long long) m->last_block, m->block_size,

+		m->io_align);

+

+  /* Ensure required buffer alignment is a power of two (or is zero). */

+  if (m->io_align & (m->io_align - 1))

+    return grub_error (GRUB_ERR_IO, "invalid buffer alignment %d", m->io_align);

+

   disk->total_sectors = m->last_block + 1;

   /* Don't increase this value due to bug in some EFI.  */

   disk->max_agglomerate = 0xa0000 >> (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS);

@@ -518,15 +525,42 @@ grub_efidisk_readwrite (struct grub_disk *disk, grub_disk_addr_t sector,

 {

   struct grub_efidisk_data *d;

   grub_efi_block_io_t *bio;

+  grub_efi_status_t status;

+  grub_size_t io_align, num_bytes;

+  char *aligned_buf;

   d = disk->data;

   bio = d->block_io;

-  return efi_call_5 ((wr ? bio->write_blocks : bio->read_blocks), bio,

-		     bio->media->media_id,

-		     (grub_efi_uint64_t) sector,

-		     (grub_efi_uintn_t) size << disk->log_sector_size,

-		     buf);

+  /* Set alignment to 1 if 0 specified */

+  io_align = bio->media->io_align ? bio->media->io_align : 1;

+  num_bytes = size << disk->log_sector_size;

+

+  if ((grub_addr_t) buf & (io_align - 1))

+    {

+      aligned_buf = grub_memalign (io_align, num_bytes);

+      if (! aligned_buf)

+	return GRUB_EFI_OUT_OF_RESOURCES;

+      if (wr)

+	grub_memcpy (aligned_buf, buf, num_bytes);

+    }

+  else

+    {

+      aligned_buf = buf;

+    }

+

+  status =  efi_call_5 ((wr ? bio->write_blocks : bio->read_blocks), bio,

+			bio->media->media_id, (grub_efi_uint64_t) sector,

+			(grub_efi_uintn_t) num_bytes, aligned_buf);

+

+  if ((grub_addr_t) buf & (io_align - 1))

+    {

+      if (!wr)

+	grub_memcpy (buf, aligned_buf, num_bytes);

+      grub_free (aligned_buf);

+    }

+

+  return status;

 }

 static grub_err_t