libpayload/corebootfb: Fix character buffer relocation

The `chars` pointer references the heap which is part of the payload
and relocated along with it. So calling phys_to_virt() on it was
always wrong; and the virt_to_phys() at its initialization was a
no-op anyway, when the console was brought up before relocation.

While we are at it, add a null-pointer check.

Change-Id: Ic03150f0bcd14a6ec6bf514dffe2b9153d5a6d2a
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38536
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 6 insertions, 5 deletions

diff --git a/payloads/libpayload/drivers/video/corebootfb.c b/payloads/libpayload/drivers/video/corebootfb.c
index b5ad1a511d..11397ba905 100644
--- a/payloads/libpayload/drivers/video/corebootfb.c
+++ b/payloads/libpayload/drivers/video/corebootfb.c
@@ -64,11 +64,11 @@ static const u32 vga_colors[] = {
 /* Addresses for the various components */
 static unsigned long fbinfo;
 static unsigned long fbaddr;
-static unsigned long chars;
+static unsigned short *chars;
 
 #define FI ((struct cb_framebuffer *) phys_to_virt(fbinfo))
 #define FB ((unsigned char *) phys_to_virt(fbaddr))
-#define CHARS ((unsigned short *) phys_to_virt(chars))
+#define CHARS (chars)
 
 static void corebootfb_scroll_up(void)
 {
@@ -243,9 +243,10 @@ static int corebootfb_init(void)
 	coreboot_video_console.columns = FI->x_resolution / font_width;
 	coreboot_video_console.rows = FI->y_resolution / font_height;
 
-	/* See setting of fbinfo above. */
-	chars = virt_to_phys(malloc(coreboot_video_console.rows *
-				    coreboot_video_console.columns * 2));
+	chars = malloc(coreboot_video_console.rows *
+		       coreboot_video_console.columns * 2);
+	if (!chars)
+		return -1;
 
 	// clear boot splash screen if there is one.
 	corebootfb_clear();