cbfs: Fix overwalk on file scan

A bootblock overwalk was occuring when deriving the actual
length, the bootblock size was not taken into account and bootblock
size was not aligned.

Resolved merge conflict.

Change-Id: I7eb42f8deaaf223dcf07b37bb7dde4643acd508f
Signed-off-by: Steven Sherk <steven.sherk@se-eng.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/65989
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Commit-Queue: Steve Sherk <ssherk70@gmail.com>
Tested-by: Steve Sherk <ssherk70@gmail.com>
(cherry picked from commit 20b0ba479b01755fbdc7f3dd9214e8af923402ba)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6539
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
diff --git a/payloads/libpayload/libcbfs/cbfs_core.c b/payloads/libpayload/libcbfs/cbfs_core.c
index a3d3e02..fb15744 100644
--- a/payloads/libpayload/libcbfs/cbfs_core.c
+++ b/payloads/libpayload/libcbfs/cbfs_core.c
@@ -119,11 +119,22 @@
 	// TODO Add a "size" in CBFS header for a platform independent way to
 	// determine the end of CBFS data.
 #if defined(CONFIG_LP_ARCH_X86) && CONFIG_LP_ARCH_X86
-	romsize -= htonl(header->bootblocksize);
-#endif
-	DEBUG("CBFS location: 0x%x~0x%x, align: %d\n", offset, romsize, align);
+	// resolve actual length of ROM used for CBFS components
+	// the bootblock size was not taken into account
+	romsize -= ntohl(header->bootblocksize);
 
+	// fine tune the length to handle alignment positioning.
+	// using (bootblock size) % align, to derive the
+	// number of bytes the bootblock is off from the alignment size.
+	if ((ntohl(header->bootblocksize) % align))
+		romsize -= (align - (ntohl(header->bootblocksize) % align));
+	else
+		romsize -= 1;
+#endif
+
+	DEBUG("CBFS location: 0x%x~0x%x, align: %d\n", offset, romsize, align);
 	DEBUG("Looking for '%s' starting from 0x%x.\n", name, offset);
+
 	media->open(media);
 	while (offset < romsize &&
 	       media->read(media, &file, offset, sizeof(file)) == sizeof(file)) {