[08/11] coverity: tty_ldisc_ref return null check

[Greg KH <gregkh@suse.de>]

-stable review patch.  If anyone has any objections, please let us know.

------------------

From: KAMBAROV, ZAUR <kambarov@berkeley.edu>

We add a check of the return value of tty_ldisc_ref(), which
is checked 7 out of 8 times, e.g.:

149  		ld = tty_ldisc_ref(tty);
150  		if (ld != NULL) {
151  			if (ld->set_termios)
152  				(ld->set_termios)(tty, &old_termios);
153  			tty_ldisc_deref(ld);
154  		}

This defect was found automatically by Coverity Prevent, a static analysis
tool.

(akpm: presumably `ld' is never NULL.  Oh well)

Signed-off-by: Zaur Kambarov <zkambarov@coverity.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 drivers/char/tty_ioctl.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

--- linux-2.6.12.2.orig/drivers/char/tty_ioctl.c	2005-06-17 12:48:29.000000000 -0700
+++ linux-2.6.12.2/drivers/char/tty_ioctl.c	2005-07-13 10:56:39.000000000 -0700
@@ -476,11 +476,11 @@
 			ld = tty_ldisc_ref(tty);
 			switch (arg) {
 			case TCIFLUSH:
-				if (ld->flush_buffer)
+				if (ld && ld->flush_buffer)
 					ld->flush_buffer(tty);
 				break;
 			case TCIOFLUSH:
-				if (ld->flush_buffer)
+				if (ld && ld->flush_buffer)
 					ld->flush_buffer(tty);
 				/* fall through */
 			case TCOFLUSH:
-
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