[PATCH] coverity: tty_ldisc_ref return null check

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>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index 58597993954f7e8fea638d065afdc7a5362e2ed5..f19cf9d7792d57816b53cf0e697bda80fe07a50e 100644 (file)
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -476,11 +476,11 @@ int n_tty_ioctl(struct tty_struct * tty, struct file * file,
                        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: