linux-kernel - [PATCH] Libertas: fix buffer overflow in lbs_get

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Message-Id: <1260936778-2096-1-git-send-email-daniel@caiaq.de>
Date:	Wed, 16 Dec 2009 05:12:58 +0100
From:	Daniel Mack <daniel@...aq.de>
To:	linux-kernel@...r.kernel.org
Cc:	Daniel Mack <daniel@...aq.de>, Dan Williams <dcbw@...hat.com>,
	Holger Schurig <holgerschurig@...il.com>,
	"John W. Linville" <linville@...driver.com>,
	Stephen Hemminger <shemminger@...tta.com>,
	Maithili Hinge <maithili@...vell.com>,
	Kiran Divekar <dkiran@...vell.com>,
	Michael Hirsch <m.hirsch@...mfeld.com>, netdev@...r.kernel.org,
	libertas-dev@...ts.infradead.org,
	linux-wireless@...ts.infradead.org, stable@...nel.org
Subject: [PATCH] Libertas: fix buffer overflow in lbs_get_essid()

The libertas driver copies the SSID buffer back to the wireless core and
appends a trailing NULL character for termination. This is

a) unnecessary because the buffer is allocated with kzalloc and is hence
   already NULLed when this function is called, and

b) for priv->curbssparams.ssid_len == 32, it writes back one byte too
   much which causes memory corruptions.

Fix this by removing the extra write.

Signed-off-by: Daniel Mack <daniel@...aq.de>
Cc: Dan Williams <dcbw@...hat.com>
Cc: Holger Schurig <holgerschurig@...il.com>
Cc: John W. Linville <linville@...driver.com>
Cc: Stephen Hemminger <shemminger@...tta.com>
Cc: Maithili Hinge <maithili@...vell.com>
Cc: Kiran Divekar <dkiran@...vell.com>
Cc: Michael Hirsch <m.hirsch@...mfeld.com>
Cc: netdev@...r.kernel.org
Cc: libertas-dev@...ts.infradead.org
Cc: linux-wireless@...ts.infradead.org
Cc: stable@...nel.org
---
 drivers/net/wireless/libertas/wext.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/libertas/wext.c b/drivers/net/wireless/libertas/wext.c
index be837a0..01c738b 100644
--- a/drivers/net/wireless/libertas/wext.c
+++ b/drivers/net/wireless/libertas/wext.c
@@ -1953,10 +1953,8 @@ static int lbs_get_essid(struct net_device *dev, struct iw_request_info *info,
 	if (priv->connect_status == LBS_CONNECTED) {
 		memcpy(extra, priv->curbssparams.ssid,
 		       priv->curbssparams.ssid_len);
-		extra[priv->curbssparams.ssid_len] = '\0';
 	} else {
 		memset(extra, 0, 32);
-		extra[priv->curbssparams.ssid_len] = '\0';
 	}
 	/*
 	 * If none, we may want to get the one that was set
-- 
1.6.3.3

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