From d0aaa57df2d8f5d355c64935dcff58cd4ab9fe2f Mon Sep 17 00:00:00 2001 From: Larry Finger Date: Mon, 4 Jan 2016 20:30:58 -0600 Subject: [PATCH] staging: r8192U: Fix check pointer after usage problem In routine rtl8192_tx_isr(), pointer skb is dereferenced before it is checked for NULL. This patch has only been compile-tested, as I do not have the hardware. This problem was reported at https://bugzilla.kernel.org/show_bug.cgi?id=109951. Fixes: bugzilla.kernel.org: #109951 Reported-by: Yong Shi Signed-off-by: Larry Finger Cc: Yong Shi Signed-off-by: Greg Kroah-Hartman --- drivers/staging/rtl8192u/r8192U_core.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/staging/rtl8192u/r8192U_core.c b/drivers/staging/rtl8192u/r8192U_core.c index 07f4e7a5469a..3c589636139a 100644 --- a/drivers/staging/rtl8192u/r8192U_core.c +++ b/drivers/staging/rtl8192u/r8192U_core.c @@ -1092,10 +1092,17 @@ static int rtl8192_hard_start_xmit(struct sk_buff *skb, struct net_device *dev) static void rtl8192_tx_isr(struct urb *tx_urb) { struct sk_buff *skb = (struct sk_buff *)tx_urb->context; - struct net_device *dev = (struct net_device *)(skb->cb); + struct net_device *dev; struct r8192_priv *priv = NULL; - cb_desc *tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE); - u8 queue_index = tcb_desc->queue_index; + cb_desc *tcb_desc; + u8 queue_index; + + if (!skb) + return; + + dev = (struct net_device *)(skb->cb); + tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE); + queue_index = tcb_desc->queue_index; priv = ieee80211_priv(dev); @@ -1113,11 +1120,9 @@ static void rtl8192_tx_isr(struct urb *tx_urb) } /* free skb and tx_urb */ - if (skb != NULL) { - dev_kfree_skb_any(skb); - usb_free_urb(tx_urb); - atomic_dec(&priv->tx_pending[queue_index]); - } + dev_kfree_skb_any(skb); + usb_free_urb(tx_urb); + atomic_dec(&priv->tx_pending[queue_index]); /* * Handle HW Beacon: -- 2.30.2