[PATCH 5.4 177/184] tty: fix memory leak in vc_deallocate

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Pavel Skripkin <paskripkin@xxxxxxxxx>

commit 211b4d42b70f1c1660feaa968dac0efc2a96ac4d upstream.

syzbot reported memory leak in tty/vt.
The problem was in VT_DISALLOCATE ioctl cmd.
After allocating unimap with PIO_UNIMAP it wasn't
freed via VT_DISALLOCATE, but vc_cons[currcons].d was
zeroed.

Reported-by: syzbot+bcc922b19ccc64240b42@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210327214443.21548-1-paskripkin@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/tty/vt/vt.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1377,6 +1377,7 @@ struct vc_data *vc_deallocate(unsigned i
 		atomic_notifier_call_chain(&vt_notifier_list, VT_DEALLOCATE, &param);
 		vcs_remove_sysfs(currcons);
 		visual_deinit(vc);
+		con_free_unimap(vc);
 		put_pid(vc->vt_pid);
 		vc_uniscr_set(vc, NULL);
 		kfree(vc->vc_screenbuf);