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>

diff --git a/drivers/video/uvesafb.c b/drivers/video/uvesafb.c
index c288270..0b370ae 100644 (file)
--- 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.