linux-kernel - [PATCH] staging: line6: toneport.c: Fix for possible null pointer dereference

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Message-Id: <1419201796-13790-1-git-send-email-rickard_strandqvist@spectrumdigital.se>
Date:	Sun, 21 Dec 2014 23:43:16 +0100
From:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jerry Snitselaar <dev@...tselaar.org>
Cc:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>,
	Fabian Mewes <architekt@...ing4coffee.org>,
	Stefan Hajnoczi <stefanha@...il.com>,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: [PATCH] staging: line6: toneport.c:  Fix for possible null pointer dereference

The NULL check was done to late, and there it was a risk
of a possible null pointer dereference.

This was partially found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
---
 drivers/staging/line6/toneport.c |   15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/line6/toneport.c b/drivers/staging/line6/toneport.c
index 6943715..660dc3f 100644
--- a/drivers/staging/line6/toneport.c
+++ b/drivers/staging/line6/toneport.c
@@ -433,12 +433,16 @@ void line6_toneport_reset_resume(struct usb_line6_toneport *toneport)
 void line6_toneport_disconnect(struct usb_interface *interface)
 {
 	struct usb_line6_toneport *toneport;
+	struct snd_line6_pcm *line6pcm;
 	u16 idProduct;
 
 	if (interface == NULL)
 		return;
 
 	toneport = usb_get_intfdata(interface);
+	if (NULL == toneport)
+		return;
+
 	del_timer_sync(&toneport->timer);
 	idProduct = le16_to_cpu(toneport->line6.usbdev->descriptor.idProduct);
 
@@ -447,13 +451,10 @@ void line6_toneport_disconnect(struct usb_interface *interface)
 		device_remove_file(&interface->dev, &dev_attr_led_green);
 	}
 
-	if (toneport != NULL) {
-		struct snd_line6_pcm *line6pcm = toneport->line6.line6pcm;
-
-		if (line6pcm != NULL) {
-			line6_pcm_release(line6pcm, LINE6_BITS_PCM_MONITOR);
-			line6_pcm_disconnect(line6pcm);
-		}
+	line6pcm = toneport->line6.line6pcm;
+	if (line6pcm != NULL) {
+		line6_pcm_release(line6pcm, LINE6_BITS_PCM_MONITOR);
+		line6_pcm_disconnect(line6pcm);
 	}
 
 	toneport_destruct(interface);
-- 
1.7.10.4

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