libpayload: cbfs: Fix ram_media map() error return value

The correct return value for errors on a cbfs_media->map() call is
CBFS_MEDIA_INVALID_MAP_ADDRESS, not NULL. Not sure if that's the best
choice (since 0xffffffff is probably a more likely valid address than 0
there), but that's what the upper layers expect right now.

BRANCH=veyron
BUG=None
TEST=Press CTRL+L with an RW_LEGACY section filled with 0xff. Observe
how cbfs_get_header() returns failure without doing a bunch of NULL
pointer accesses first (not that those have any visible effect on
Veyron, but that's another problem...)

Change-Id: I3d012fc9af9da6e01159990a6bdd62c38fc22329
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 3a609e17bb9b0ef4d3a833f72fa4fbfd8e8cb0ab
Original-Change-Id: I0793434116a8c568e19fe0dee24f13942fc50f25
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/238991
Original-Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/8758
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/payloads/libpayload/libcbfs/ram_media.c b/payloads/libpayload/libcbfs/ram_media.c
index 3d9abf0fbeec..d5469f68905b 100644
--- a/payloads/libpayload/libcbfs/ram_media.c
+++ b/payloads/libpayload/libcbfs/ram_media.c
@@ -51,7 +51,7 @@ static void *ram_map(struct cbfs_media *media, size_t offset, size_t count) {
 	if (offset + count > m->size) {
 		printf("ERROR: ram_map: request out of range (0x%zx+0x%zx)\n",
 		       offset, count);
-		return NULL;
+		return CBFS_MEDIA_INVALID_MAP_ADDRESS;
 	}
 	return (void*)(m->start + offset);
 }
@@ -63,6 +63,8 @@ static void *ram_unmap(struct cbfs_media *media, const void *address) {
 static size_t ram_read(struct cbfs_media *media, void *dest, size_t offset,
 			   size_t count) {
 	void *ptr = ram_map(media, offset, count);
+	if (ptr == CBFS_MEDIA_INVALID_MAP_ADDRESS)
+		return 0;
 	memcpy(dest, ptr, count);
 	ram_unmap(media, ptr);
 	return count;