[PATCH 4.19 112/425] tty: fix memory leak in vc_deallocate

From: Greg Kroah-Hartman
Date: Thu May 20 2021 - 05:49:38 EST


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
@@ -1380,6 +1380,7 @@ 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);