From 7098296a362a96051fa120abf48f0095818b99cd Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Thu, 17 Sep 2015 17:17:08 +0200 Subject: [PATCH] tty: fix data race in flush_to_ldisc flush_to_ldisc reads port->itty and checks that it is not NULL, concurrently release_tty sets port->itty to NULL. It is possible that flush_to_ldisc loads port->itty once, ensures that it is not NULL, but then reloads it again and uses. The second load can already return NULL, which will cause a crash. Use READ_ONCE to read port->itty. The data race was found with KernelThreadSanitizer (KTSAN). Signed-off-by: Dmitry Vyukov Reviewed-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index 5a3fa89..23de97d 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -467,7 +467,7 @@ static void flush_to_ldisc(struct work_struct *work) struct tty_struct *tty; struct tty_ldisc *disc; - tty = port->itty; + tty = READ_ONCE(port->itty); if (tty == NULL) return; -- 2.7.4