netdev - Re: gigaset: memory leak in gigaset

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Date:	Fri, 05 Feb 2016 19:36:01 +0100
From:	Paul Bolle <pebolle@...cali.nl>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	Karsten Keil <isdn@...ux-pingi.de>,
	"David S. Miller" <davem@...emloft.net>,
	gigaset307x-common@...ts.sourceforge.net, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, syzkaller@...glegroups.com,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>
Subject: Re: gigaset: memory leak in gigaset_initcshw

On vr, 2016-02-05 at 17:06 +0100, Paul Bolle wrote:
> If that would happen, then cs can be reused while the previous
> > cs->hw.ser is not freed yet. Just a guess.
> 
> I'll have to ponder on that a bit, sorry.

This is from the hit-the-code-until-it-confesses department:
--- a/drivers/isdn/gigaset/ser-gigaset.c
+++ b/drivers/isdn/gigaset/ser-gigaset.c
@@ -373,13 +373,9 @@ static void gigaset_freecshw(struct cardstate *cs)
 
 static void gigaset_device_release(struct device *dev)
 {
-       struct cardstate *cs = dev_get_drvdata(dev);
-
-       if (!cs)
-               return;
+       struct ser_cardstate *scs = dev_get_drvdata(dev);
        dev_set_drvdata(dev, NULL);
-       kfree(cs->hw.ser);
-       cs->hw.ser = NULL;
+       kfree(scs);
 }
 
 /*
@@ -408,7 +404,7 @@ static int gigaset_initcshw(struct cardstate *cs)
                cs->hw.ser = NULL;
                return rc;
        }
-       dev_set_drvdata(&cs->hw.ser->dev.dev, cs);
+       dev_set_drvdata(&cs->hw.ser->dev.dev, scs);
 
        tasklet_init(&cs->write_tasklet,
                     gigaset_modem_fill, (unsigned long) cs);

Does that make any difference?


Paul Bolle