tty: warn on deprecated serial flags
When somebody calls TIOCSSERIAL ioctl with serial flags to set one of
* ASYNC_SESSION_LOCKOUT
* ASYNC_PGRP_LOCKOUT
* ASYNC_CALLOUT_NOHUP
* ASYNC_AUTOPROBE
nothing happens. We actually ignore the flags for over a decade at
least (I checked 2.6.0).
So start yelling at users who use those flags, that they shouldn't.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 01d45fd..7058858 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2760,6 +2760,24 @@
return 0;
}
+static void tty_warn_deprecated_flags(struct serial_struct __user *ss)
+{
+ static DEFINE_RATELIMIT_STATE(depr_flags,
+ DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);
+ char comm[TASK_COMM_LEN];
+ int flags;
+
+ if (get_user(flags, &ss->flags))
+ return;
+
+ flags &= ASYNC_DEPRECATED;
+
+ if (flags && __ratelimit(&depr_flags))
+ pr_warning("%s: '%s' is using deprecated serial flags (with no effect): %.8x\n",
+ __func__, get_task_comm(comm, current), flags);
+}
+
/*
* if pty, return the slave side (real_tty)
* otherwise, return self
@@ -2903,6 +2921,9 @@
break;
}
break;
+ case TIOCSSERIAL:
+ tty_warn_deprecated_flags(p);
+ break;
}
if (tty->ops->ioctl) {
retval = tty->ops->ioctl(tty, cmd, arg);