Fix LDM for new field in the VOL5 VBLK.

Teach LDM about a new field encountered with Windows Vista.

This fixes LDM for people using Vista who have disabled drive letter
assignment from one or more volumes.  Doing this introduces a so far
unknown field in the LDM database in the VOL5 VBLK structure which
causes the LDM driver to fail to parse the VBLK structure and hence LDM
fails to parse the disk altogether.  This patch teaches the driver about
this field.

Thanks got to Ashton Mills <amills@iinet.com.au> for reporting the
problem and working with me on getting it fixed.  It is now working for
him.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
CC: Richard Russon <ldm@flatcap.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 93 insertions, 46 deletions

diff --git a/fs/partitions/ldm.c b/fs/partitions/ldm.c
index 99873a2..e7dd1d4 100644
--- a/fs/partitions/ldm.c
+++ b/fs/partitions/ldm.c
@@ -677,15 +677,24 @@ static bool ldm_create_data_partitions (struct parsed_partitions *pp,
  * Return:  -1 Error, the calculated offset exceeded the size of the buffer
  *           n OK, a range-checked offset into buffer
  */
-static int ldm_relative (const u8 *buffer, int buflen, int base, int offset)
+static int ldm_relative(const u8 *buffer, int buflen, int base, int offset)
 {
 
 	base += offset;
-	if ((!buffer) || (offset < 0) || (base > buflen))
+	if (!buffer || offset < 0 || base > buflen) {
+		if (!buffer)
+			ldm_error("!buffer");
+		if (offset < 0)
+			ldm_error("offset (%d) < 0", offset);
+		if (base > buflen)
+			ldm_error("base (%d) > buflen (%d)", base, buflen);
 		return -1;
-	if ((base + buffer[base]) >= buflen)
+	}
+	if (base + buffer[base] >= buflen) {
+		ldm_error("base (%d) + buffer[base] (%d) >= buflen (%d)", base,
+				buffer[base], buflen);
 		return -1;
-
+	}
 	return buffer[base] + offset + 1;
 }
 
@@ -1054,60 +1063,98 @@ static bool ldm_parse_prt3(const u8 *buffer, int buflen, struct vblk *vb)
  * Return:  'true'   @vb contains a Volume VBLK
  *          'false'  @vb contents are not defined
  */
-static bool ldm_parse_vol5 (const u8 *buffer, int buflen, struct vblk *vb)
+static bool ldm_parse_vol5(const u8 *buffer, int buflen, struct vblk *vb)
 {
-	int r_objid, r_name, r_vtype, r_child, r_size, r_id1, r_id2, r_size2;
-	int r_drive, len;
+	int r_objid, r_name, r_vtype, r_disable_drive_letter, r_child, r_size;
+	int r_id1, r_id2, r_size2, r_drive, len;
 	struct vblk_volu *volu;
 
-	BUG_ON (!buffer || !vb);
-
-	r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
-	r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);
-	r_vtype  = ldm_relative (buffer, buflen, 0x18, r_name);
-	r_child  = ldm_relative (buffer, buflen, 0x2E, r_vtype);
-	r_size   = ldm_relative (buffer, buflen, 0x3E, r_child);
-
-	if (buffer[0x12] & VBLK_FLAG_VOLU_ID1)
-		r_id1 = ldm_relative (buffer, buflen, 0x53, r_size);
-	else
+	BUG_ON(!buffer || !vb);
+	r_objid = ldm_relative(buffer, buflen, 0x18, 0);
+	if (r_objid < 0) {
+		ldm_error("r_objid %d < 0", r_objid);
+		return false;
+	}
+	r_name = ldm_relative(buffer, buflen, 0x18, r_objid);
+	if (r_name < 0) {
+		ldm_error("r_name %d < 0", r_name);
+		return false;
+	}
+	r_vtype = ldm_relative(buffer, buflen, 0x18, r_name);
+	if (r_vtype < 0) {
+		ldm_error("r_vtype %d < 0", r_vtype);
+		return false;
+	}
+	r_disable_drive_letter = ldm_relative(buffer, buflen, 0x18, r_vtype);
+	if (r_disable_drive_letter < 0) {
+		ldm_error("r_disable_drive_letter %d < 0",
+				r_disable_drive_letter);
+		return false;
+	}
+	r_child = ldm_relative(buffer, buflen, 0x2D, r_disable_drive_letter);
+	if (r_child < 0) {
+		ldm_error("r_child %d < 0", r_child);
+		return false;
+	}
+	r_size = ldm_relative(buffer, buflen, 0x3D, r_child);
+	if (r_size < 0) {
+		ldm_error("r_size %d < 0", r_size);
+		return false;
+	}
+	if (buffer[0x12] & VBLK_FLAG_VOLU_ID1) {
+		r_id1 = ldm_relative(buffer, buflen, 0x52, r_size);
+		if (r_id1 < 0) {
+			ldm_error("r_id1 %d < 0", r_id1);
+			return false;
+		}
+	} else
 		r_id1 = r_size;
-
-	if (buffer[0x12] & VBLK_FLAG_VOLU_ID2)
-		r_id2 = ldm_relative (buffer, buflen, 0x53, r_id1);
-	else
+	if (buffer[0x12] & VBLK_FLAG_VOLU_ID2) {
+		r_id2 = ldm_relative(buffer, buflen, 0x52, r_id1);
+		if (r_id2 < 0) {
+			ldm_error("r_id2 %d < 0", r_id2);
+			return false;
+		}
+	} else
 		r_id2 = r_id1;
-
-	if (buffer[0x12] & VBLK_FLAG_VOLU_SIZE)
-		r_size2 = ldm_relative (buffer, buflen, 0x53, r_id2);
-	else
+	if (buffer[0x12] & VBLK_FLAG_VOLU_SIZE) {
+		r_size2 = ldm_relative(buffer, buflen, 0x52, r_id2);
+		if (r_size2 < 0) {
+			ldm_error("r_size2 %d < 0", r_size2);
+			return false;
+		}
+	} else
 		r_size2 = r_id2;
-
-	if (buffer[0x12] & VBLK_FLAG_VOLU_DRIVE)
-		r_drive = ldm_relative (buffer, buflen, 0x53, r_size2);
-	else
+	if (buffer[0x12] & VBLK_FLAG_VOLU_DRIVE) {
+		r_drive = ldm_relative(buffer, buflen, 0x52, r_size2);
+		if (r_drive < 0) {
+			ldm_error("r_drive %d < 0", r_drive);
+			return false;
+		}
+	} else
 		r_drive = r_size2;
-
 	len = r_drive;
-	if (len < 0)
+	if (len < 0) {
+		ldm_error("len %d < 0", len);
 		return false;
-
+	}
 	len += VBLK_SIZE_VOL5;
-	if (len != BE32 (buffer + 0x14))
+	if (len > BE32(buffer + 0x14)) {
+		ldm_error("len %d > BE32(buffer + 0x14) %d", len,
+				BE32(buffer + 0x14));
 		return false;
-
+	}
 	volu = &vb->vblk.volu;
-
-	ldm_get_vstr (buffer + 0x18 + r_name,  volu->volume_type,
-		sizeof (volu->volume_type));
-	memcpy (volu->volume_state, buffer + 0x19 + r_vtype,
-			sizeof (volu->volume_state));
-	volu->size = ldm_get_vnum (buffer + 0x3E + r_child);
-	volu->partition_type = buffer[0x42 + r_size];
-	memcpy (volu->guid, buffer + 0x43 + r_size,  sizeof (volu->guid));
+	ldm_get_vstr(buffer + 0x18 + r_name, volu->volume_type,
+			sizeof(volu->volume_type));
+	memcpy(volu->volume_state, buffer + 0x18 + r_disable_drive_letter,
+			sizeof(volu->volume_state));
+	volu->size = ldm_get_vnum(buffer + 0x3D + r_child);
+	volu->partition_type = buffer[0x41 + r_size];
+	memcpy(volu->guid, buffer + 0x42 + r_size, sizeof(volu->guid));
 	if (buffer[0x12] & VBLK_FLAG_VOLU_DRIVE) {
-		ldm_get_vstr (buffer + 0x53 + r_size,  volu->drive_hint,
-			sizeof (volu->drive_hint));
+		ldm_get_vstr(buffer + 0x52 + r_size, volu->drive_hint,
+				sizeof(volu->drive_hint));
 	}
 	return true;
 }
diff --git a/fs/partitions/ldm.h b/fs/partitions/ldm.h
index d2e6a30..80f63b5 100644
--- a/fs/partitions/ldm.h
+++ b/fs/partitions/ldm.h
@@ -68,7 +68,7 @@ struct parsed_partitions;
 #define VBLK_SIZE_DSK3		12
 #define VBLK_SIZE_DSK4		45
 #define VBLK_SIZE_PRT3		28
-#define VBLK_SIZE_VOL5		59
+#define VBLK_SIZE_VOL5		58
 
 /* component types */
 #define COMP_STRIPE		0x01		/* Stripe-set */