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tty: Prevent tty teardown during tty_write_message()

tty_write_message() allows the caller to directly write to a specific
tty. Since the line discipline is bypassed for the direct write,
nothing prevents the tty from being torn down after the tty count is
checked.

Hold the tty lock for the duration of the direct write.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Peter Hurley 9 жил өмнө
parent
commit
4b41b9539a
1 өөрчлөгдсөн 2 нэмэгдсэн , 4 устгасан
  1. 2 4
      drivers/tty/tty_io.c

+ 2 - 4
drivers/tty/tty_io.c

@@ -1200,11 +1200,9 @@ void tty_write_message(struct tty_struct *tty, char *msg)
 	if (tty) {
 		mutex_lock(&tty->atomic_write_lock);
 		tty_lock(tty);
-		if (tty->ops->write && tty->count > 0) {
-			tty_unlock(tty);
+		if (tty->ops->write && tty->count > 0)
 			tty->ops->write(tty, msg, strlen(msg));
-		} else
-			tty_unlock(tty);
+		tty_unlock(tty);
 		tty_write_unlock(tty);
 	}
 	return;