[34-longterm 212/247] USB: cdc-acm: fix potential null-pointer dereference

[Paul Gortmaker]

From: Johan Hovold <jhovold@xxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit 15e5bee33ffc11d0e5c6f819a65e7881c5c407be upstream.

Must check return value of tty_port_tty_get.

Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 drivers/usb/class/cdc-acm.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 073a9ef..af5ed89 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -534,6 +534,8 @@ static void acm_softint(struct work_struct *work)
 	if (!ACM_READY(acm))
 		return;
 	tty = tty_port_tty_get(&acm->port);
+	if (!tty)
+		return;
 	tty_wakeup(tty);
 	tty_kref_put(tty);
 }
-- 
1.7.4.4

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