[PATCH] tty/vt: don't set font mappings on vc not supporting this

[Imre Deak <imre.deak@intel.com>]

We can call this function for a dummy console that doesn't support
setting the font mapping, which will result in a null ptr BUG. So check
for this case and return error for consoles w/o font mapping support.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=59321
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/tty/vt/consolemap.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
index 610b720..59b25e0 100644
--- a/drivers/tty/vt/consolemap.c
+++ b/drivers/tty/vt/consolemap.c
@@ -539,6 +539,12 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 
 	/* Save original vc_unipagdir_loc in case we allocate a new one */
 	p = *vc->vc_uni_pagedir_loc;
+
+	if (!p) {
+		err = -EINVAL;
+
+		goto out_unlock;
+	}
 	
 	if (p->refcount > 1) {
 		int j, k;
@@ -623,6 +629,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 		set_inverse_transl(vc, p, i); /* Update inverse translations */
 	set_inverse_trans_unicode(vc, p);
 
+out_unlock:
 	console_unlock();
 	return err;
 }
-- 
1.8.4