uvesafb: fix selecting mode with the vbemode option

If the vbemode option is used, uvesafb calls fb_get_mode() without first
setting the resolution in info->var.  This results in a division by zero
in fb_get_mode(), as evidenced e.g.  in [1].  Fix this by ensuring the
info->var structure is populated before fb_get_mode() is called.

[1] http://bugzilla.kernel.org/show_bug.cgi?id=11661#c37

Signed-off-by: Michal Januszewski <spock@gentoo.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/video/uvesafb.c b/drivers/video/uvesafb.c
index c288270e42f7..0b370aebdbfd 100644
--- a/drivers/video/uvesafb.c
+++ b/drivers/video/uvesafb.c
@@ -850,14 +850,16 @@ static int __devinit uvesafb_vbe_init_mode(struct fb_info *info)
         if (vbemode) {
                 for (i = 0; i < par->vbe_modes_cnt; i++) {
                         if (par->vbe_modes[i].mode_id == vbemode) {
+                                modeid = i;
+                                uvesafb_setup_var(&info->var, info,
+                                                &par->vbe_modes[modeid]);
                                 fb_get_mode(FB_VSYNCTIMINGS | FB_IGNOREMON, 60,
-                                                        &info->var, info);
+                                                &info->var, info);
                                 /*
                                  * With pixclock set to 0, the default BIOS
                                  * timings will be used in set_par().
                                  */
                                 info->var.pixclock = 0;
-                                modeid = i;
                                 goto gotmode;
                         }
                 }
@@ -904,8 +906,11 @@ static int __devinit uvesafb_vbe_init_mode(struct fb_info *info)
                         fb_videomode_to_var(&info->var, mode);
                 } else {
                         modeid = par->vbe_modes[0].mode_id;
+                        uvesafb_setup_var(&info->var, info,
+                                        &par->vbe_modes[modeid]);
                         fb_get_mode(FB_VSYNCTIMINGS | FB_IGNOREMON, 60,
-                                    &info->var, info);
+                                        &info->var, info);
+
                         goto gotmode;
                 }
         }
@@ -917,9 +922,9 @@ static int __devinit uvesafb_vbe_init_mode(struct fb_info *info)
         if (modeid == -1)
                 return -EINVAL;
 
-gotmode:
         uvesafb_setup_var(&info->var, info, &par->vbe_modes[modeid]);
 
+gotmode:
         /*
          * If we are not VBE3.0+ compliant, we're done -- the BIOS will
          * ignore our timings anyway.