drivers: video: fbcon: fix NULL dereference in fbcon_cursor()

add null-check on function pointer before dereference on ops->cursor

Reported-by: syzbot+b67aaae8d3a927f68d20@syzkaller.appspotmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Du Cheng <ducheng2@gmail.com>
Link: https://lore.kernel.org/r/20210312081421.452405-1-ducheng2@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 44a5cd2f54ccce9acb164685910c2e78d3a04823..3406067985b1f3fbe3c379f86a2e2233d6757d94 100644 (file)
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -1333,6 +1333,9 @@ static void fbcon_cursor(struct vc_data *vc, int mode)
 
        ops->cursor_flash = (mode == CM_ERASE) ? 0 : 1;
 
+       if (!ops->cursor)
+               return;
+
        ops->cursor(vc, info, mode, get_color(vc, info, c, 1),
                    get_color(vc, info, c, 0));
 }