linux-kernel - [PATCH] usb: fix uninitialized variables in keyspan

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Date:	Fri, 27 Jun 2008 10:58:54 +0300
From:	Benny Halevy <bhalevy@...asas.com>
To:	Greg KH <greg@...ah.com>
Cc:	linux-kernel@...r.kernel.org, Alen Cox <alan@...rguk.ukuu.org.uk>,
	Benny Halevy <bhalevy@...asas.com>
Subject: [PATCH] usb: fix uninitialized variables in keyspan_pda

The compiler (gcc 4.3.0) warns that status might be used uninitialized
in keyspan_pda_tiocmget and keyspan_pda_tiocmset.

It is technically correct and therefore this patch initializes
status to 0 in both cases.

Note that keyspan_pda_get_modem_info sets *value only when
usb_control_msg returns rc > 0, otherwise it must
return an error rc < 0, and it must never return rc == 0, hence
a WARN_ON(rc == 0) was added in case usb_control_msg ever return 0.

Both its callers bail out for rc < 0 and use the value
of "status" in the rc >= 0 case.  If the WARN_ON is ever seen,
status will be set to the initial value of 0.

Signed-off-by: Benny Halevy <bhalevy@...asas.com>
---
 drivers/usb/serial/keyspan_pda.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index ff54203..97ce8a3 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -420,6 +420,7 @@ static int keyspan_pda_get_modem_info(struct usb_serial *serial,
 			     3, /* get pins */
 			     USB_TYPE_VENDOR|USB_RECIP_INTERFACE|USB_DIR_IN,
 			     0, 0, &data, 1, 2000);
+	WARN_ON(rc == 0);
 	if (rc > 0)
 		*value = data;
 	return rc;
@@ -441,7 +442,7 @@ static int keyspan_pda_tiocmget(struct usb_serial_port *port, struct file *file)
 {
 	struct usb_serial *serial = port->serial;
 	int rc;
-	unsigned char status;
+	unsigned char status = 0;
 	int value;
 
 	rc = keyspan_pda_get_modem_info(serial, &status);
@@ -462,7 +463,7 @@ static int keyspan_pda_tiocmset(struct usb_serial_port *port, struct file *file,
 {
 	struct usb_serial *serial = port->serial;
 	int rc;
-	unsigned char status;
+	unsigned char status = 0;
 
 	rc = keyspan_pda_get_modem_info(serial, &status);
 	if (rc < 0)
-- 
1.5.6.GIT

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