s390/3270: fix use after free of tty3270_screen structure
The deactivation and freeing of the tty view of the 3270 device
can race with a tty3270_update invocation via the update timer.
To fix this move the del_timer_sync call for the update timer from
tty3270_free_view to tty3270_free prior to the tty3270_free_screen
call.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/tty3270.c b/drivers/s390/char/tty3270.c
index 3f4ca4e..07cf182 100644
--- a/drivers/s390/char/tty3270.c
+++ b/drivers/s390/char/tty3270.c
@@ -125,10 +125,7 @@
*/
static void tty3270_set_timer(struct tty3270 *tp, int expires)
{
- if (expires == 0)
- del_timer(&tp->timer);
- else
- mod_timer(&tp->timer, jiffies + expires);
+ mod_timer(&tp->timer, jiffies + expires);
}
/*
@@ -744,7 +741,6 @@
{
int pages;
- del_timer_sync(&tp->timer);
kbd_free(tp->kbd);
raw3270_request_free(tp->kreset);
raw3270_request_free(tp->read);
@@ -877,6 +873,7 @@
{
struct tty3270 *tp = container_of(view, struct tty3270, view);
+ del_timer_sync(&tp->timer);
tty3270_free_screen(tp->screen, tp->view.rows);
tty3270_free_view(tp);
}