viafb: improve pitch handling

This patch adds checks for minimum and maximum pitch size to prevent
invalid settings which could otherwise crash the machine. Also the
alignment is done in a slightly more readable way.

Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: stable@kernel.org

2 files changed, 13 insertions, 3 deletions

diff --git a/drivers/video/via/via_modesetting.h b/drivers/video/via/via_modesetting.h
index ae35cfdeb37c..013884543e91 100644
--- a/drivers/video/via/via_modesetting.h
+++ b/drivers/video/via/via_modesetting.h
@@ -28,6 +28,11 @@
 
 #include <linux/types.h>
 
+
+#define VIA_PITCH_SIZE  (1<<3)
+#define VIA_PITCH_MAX   0x3FF8
+
+
 void via_set_primary_address(u32 addr);
 void via_set_secondary_address(u32 addr);
 void via_set_primary_pitch(u32 pitch);
diff --git a/drivers/video/via/viafbdev.c b/drivers/video/via/viafbdev.c
index aa87529d7d6a..bddae58ecd8a 100644
--- a/drivers/video/via/viafbdev.c
+++ b/drivers/video/via/viafbdev.c
@@ -151,7 +151,8 @@ static void viafb_update_fix(struct fb_info *info)
 
         info->fix.visual =
                 bpp == 8 ? FB_VISUAL_PSEUDOCOLOR : FB_VISUAL_TRUECOLOR;
-        info->fix.line_length = (info->var.xres_virtual * bpp / 8 + 7) & ~7;
+        info->fix.line_length = ALIGN(info->var.xres_virtual * bpp / 8,
+                VIA_PITCH_SIZE);
 }
 
 static void viafb_setup_fixinfo(struct fb_fix_screeninfo *fix,
@@ -238,8 +239,12 @@ static int viafb_check_var(struct fb_var_screeninfo *var,
                 depth = 24;
 
         viafb_fill_var_color_info(var, depth);
-        line = (var->xres_virtual * var->bits_per_pixel / 8 + 7) & ~7;
-        if (line * var->yres_virtual > ppar->memsize)
+        if (var->xres_virtual < var->xres)
+                var->xres_virtual = var->xres;
+
+        line = ALIGN(var->xres_virtual * var->bits_per_pixel / 8,
+                VIA_PITCH_SIZE);
+        if (line > VIA_PITCH_MAX || line * var->yres_virtual > ppar->memsize)
                 return -EINVAL;
 
         /* Based on var passed in to calculate the refresh,