lib/fonts: Create font_data_t from struct console_font with font_data_import()

Add font_data_import() and update consoles to use it.

The implementation of font_data_import() is based on code from fbcon,
which supports overflow checks and crc32 checksums. Fbcon uses the crc32
checksum.

Newport_con now implements the same overflow checks as fbcon. As before,
this console does not support checksums, which are optional. Newport_con
can now also handle input font data with a vertical pitch other than 32
bytes. (The vertical pitch is the offset between two glyphs in the font
data.)

As an internal change, remove the const qualifier from the data field
if struct font_data. This allows font_data_import() to write the data
without type casting. For all users of the font data via font_data_t,
the stored data is still read only.

v3:
- fix typos

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>

1 files changed, 4 insertions, 34 deletions

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 00255ac92e42..53677c09a0ec 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -2039,8 +2039,6 @@ static void updatescrollmode(struct fbcon_display *p,
 	updatescrollmode_accel(p, info, vc);
 }
 
-#define PITCH(w) (((w) + 7) >> 3)
-
 static int fbcon_resize(struct vc_data *vc, unsigned int width,
 			unsigned int height, bool from_user)
 {
@@ -2424,7 +2422,6 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount,
 	resize = (w != vc->vc_font.width) || (h != vc->vc_font.height);
 	p->fontdata = data;
 	vc->vc_font.data = font_data_buf(p->fontdata);
-
 	old_width = vc->vc_font.width;
 	old_height = vc->vc_font.height;
 	old_charcount = vc->vc_font.charcount;
@@ -2482,11 +2479,8 @@ static int fbcon_set_font(struct vc_data *vc, const struct console_font *font,
 	unsigned charcount = font->charcount;
 	int w = font->width;
 	int h = font->height;
-	int size, alloc_size;
-	int i, csum, ret;
+	int i, ret;
 	font_data_t *new_data;
-	const u8 *data = font->data;
-	int pitch = PITCH(font->width);
 
 	/* Is there a reason why fbconsole couldn't handle any charcount >256?
 	 * If not this check should be changed to charcount < 256 */
@@ -2510,34 +2504,10 @@ static int fbcon_set_font(struct vc_data *vc, const struct console_font *font,
 	if (fbcon_invalid_charcount(info, charcount))
 		return -EINVAL;
 
-	/* Check for integer overflow in font size calculation */
-	if (check_mul_overflow(h, pitch, &size) ||
-	    check_mul_overflow(size, charcount, &size))
-		return -EINVAL;
-
-	/* Check for overflow in allocation size calculation */
-	if (check_add_overflow(FONT_EXTRA_WORDS * sizeof(int), size, &alloc_size))
-		return -EINVAL;
-
-	new_data = kmalloc(alloc_size, GFP_USER);
-
-	if (!new_data)
-		return -ENOMEM;
-
-	memset((u8 *)new_data, 0, FONT_EXTRA_WORDS * sizeof(int));
-
-	new_data += FONT_EXTRA_WORDS * sizeof(int);
-	FNTSIZE(new_data) = size;
-	REFCOUNT(new_data) = 1;	/* usage counter */
-	for (i=0; i< charcount; i++) {
-		memcpy((u8 *)new_data + i * h * pitch, data + i * vpitch * pitch, h * pitch);
-	}
-
-	/* Since linux has a nice crc32 function use it for counting font
-	 * checksums. */
-	csum = crc32(0, new_data, size);
+	new_data = font_data_import(font, vpitch, crc32);
+	if (IS_ERR(new_data))
+		return PTR_ERR(new_data);
 
-	FNTSUM(new_data) = csum;
 	/* Check if the same font is on some other console already */
 	for (i = first_fb_vc; i <= last_fb_vc; i++) {
 		if (fb_display[i].fontdata &&