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

Dan Williams
2009-12-16T16:58:51Z

On Wed, 2009-12-16 at 05:12 +0100, Daniel Mack wrote:
> 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.

Acked-by: Dan Williams <dcbw@redhat.com>

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