[PATCH] vgacon: Prevent faulty bootparams.screeninfo from causing harm

If a zero for the number of colums or rows manages to slip through,
gotoxy() will underflow vc->vc_pos, causing the next action on the
referenced memory to end with a page fault.

Make the check in vgacon_startup() more pessimistic to prevent that.

Signed-off-by: Jan H. Schönherr <redacted>
---
 drivers/video/console/vgacon.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index dc06cb6..445b1dc 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c

@@ -398,9 +398,8 @@ static const char *vgacon_startup(void)
 #endif
 	}
 
-	/* boot_params.screen_info initialized? */
-	if ((screen_info.orig_video_mode  = 0) &&
-	    (screen_info.orig_video_lines = 0) &&
+	/* boot_params.screen_info reasonably initialized? */
+	if ((screen_info.orig_video_lines = 0) ||
 	    (screen_info.orig_video_cols  = 0))
 		goto no_vga;
 

-- 
2.3.1.dirty