[PATCH] Libertas: fix buffer overflow in lbs_get_essid()

Daniel Mack daniel at caiaq.de
Tue Dec 15 23:12:58 EST 2009

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 at caiaq.de>
Cc: Dan Williams <dcbw at redhat.com>
Cc: Holger Schurig <holgerschurig at gmail.com>
Cc: John W. Linville <linville at tuxdriver.com>
Cc: Stephen Hemminger <shemminger at vyatta.com>
Cc: Maithili Hinge <maithili at marvell.com>
Cc: Kiran Divekar <dkiran at marvell.com>
Cc: Michael Hirsch <m.hirsch at raumfeld.com>
Cc: netdev at vger.kernel.org
Cc: libertas-dev at lists.infradead.org
Cc: linux-wireless at lists.infradead.org
Cc: stable at kernel.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,
-		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

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