[U-Boot] [PATCH 1/8] video/console: Fix DM_VIDEO font glyph array indexing

[Andre Przywara]

When the character to be printed on a DM_VIDEO console is from the
"extended ASCII" range (0x80 - 0xff), it will be treated as a negative
number, as it's declared as a signed char. This leads to negative array
indicies into the glyph bitmap array, and random garbled characters.

Cast the character to an unsigned type to make the index always positive
and avoid an out-of-bounds access.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
 drivers/video/console_normal.c | 3 ++-
 drivers/video/console_rotate.c | 7 ++++---
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/video/console_normal.c b/drivers/video/console_normal.c
index 2cfa510d5f..511589eaff 100644
--- a/drivers/video/console_normal.c
+++ b/drivers/video/console_normal.c
@@ -84,7 +84,8 @@ static int console_normal_putc_xy(struct udevice *dev, uint x_frac, uint y,
 		return -EAGAIN;
 
 	for (row = 0; row < VIDEO_FONT_HEIGHT; row++) {
-		uchar bits = video_fontdata[ch * VIDEO_FONT_HEIGHT + row];
+		unsigned int idx = (uint8_t)ch * VIDEO_FONT_HEIGHT + row;
+		uchar bits = video_fontdata[idx];
 
 		switch (vid_priv->bpix) {
 #ifdef CONFIG_VIDEO_BPP8
diff --git a/drivers/video/console_rotate.c b/drivers/video/console_rotate.c
index f076570335..e5ebaa03fa 100644
--- a/drivers/video/console_rotate.c
+++ b/drivers/video/console_rotate.c
@@ -90,7 +90,7 @@ static int console_putc_xy_1(struct udevice *dev, uint x_frac, uint y, char ch)
 	int i, col;
 	int mask = 0x80;
 	void *line;
-	uchar *pfont = video_fontdata + ch * VIDEO_FONT_HEIGHT;
+	uchar *pfont = video_fontdata + (uint8_t)ch * VIDEO_FONT_HEIGHT;
 
 	line = vid_priv->fb + (VID_TO_PIXEL(x_frac) + 1) *
 			vid_priv->line_length - (y + 1) * pbytes;
@@ -222,7 +222,8 @@ static int console_putc_xy_2(struct udevice *dev, uint x_frac, uint y, char ch)
 			VIDEO_FONT_WIDTH - 1) * VNBYTES(vid_priv->bpix);
 
 	for (row = 0; row < VIDEO_FONT_HEIGHT; row++) {
-		uchar bits = video_fontdata[ch * VIDEO_FONT_HEIGHT + row];
+		unsigned int idx = (uint8_t)ch * VIDEO_FONT_HEIGHT + row;
+		uchar bits = video_fontdata[idx];
 
 		switch (vid_priv->bpix) {
 #ifdef CONFIG_VIDEO_BPP8
@@ -348,7 +349,7 @@ static int console_putc_xy_3(struct udevice *dev, uint x_frac, uint y, char ch)
 	void *line = vid_priv->fb +
 		(vid_priv->ysize - VID_TO_PIXEL(x_frac) - 1) *
 		vid_priv->line_length + y * pbytes;
-	uchar *pfont = video_fontdata + ch * VIDEO_FONT_HEIGHT;
+	uchar *pfont = video_fontdata + (uint8_t)ch * VIDEO_FONT_HEIGHT;
 
 	if (x_frac + VID_TO_POS(vc_priv->x_charsize) > vc_priv->xsize_frac)
 		return -EAGAIN;
-- 
2.14.5