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 <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Jiri Slaby <[email protected]> Signed-off-by: Bartlomiej Zolnierkiewicz <[email protected]>
Adesh15 · Sep 4, 2017 · b9a58de · b9a58de
1 parent 58ec01c
commit b9a58de
Showing 1 changed file with 2 additions and 3 deletions.
diff --git 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;