Re: [PATCH] staging: rtl8192e: fix potential use after free

2019-11-05 Thread Dan Carpenter
On Tue, Nov 05, 2019 at 10:49:11PM +0800, Pan Bian wrote:
> The variable skb is released via kfree_skb() when the return value of
> _rtl92e_tx is not zero. However, after that, skb is accessed again to
> read its length, which may result in a use after free bug. This patch
> fixes the bug by moving the release operation to where skb is never
> used later.
> 
> Signed-off-by: Pan Bian 

Reviewed-by: Dan Carpenter 

regards,
dan carpenter

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[PATCH] staging: rtl8192e: fix potential use after free

2019-11-05 Thread Pan Bian
The variable skb is released via kfree_skb() when the return value of
_rtl92e_tx is not zero. However, after that, skb is accessed again to
read its length, which may result in a use after free bug. This patch
fixes the bug by moving the release operation to where skb is never
used later.

Signed-off-by: Pan Bian 
---
 drivers/staging/rtl8192e/rtl8192e/rtl_core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/rtl8192e/rtl8192e/rtl_core.c 
b/drivers/staging/rtl8192e/rtl8192e/rtl_core.c
index f932cb15e4e5..cdcb22f96ed9 100644
--- a/drivers/staging/rtl8192e/rtl8192e/rtl_core.c
+++ b/drivers/staging/rtl8192e/rtl8192e/rtl_core.c
@@ -1616,14 +1616,15 @@ static void _rtl92e_hard_data_xmit(struct sk_buff *skb, 
struct net_device *dev,
memcpy((unsigned char *)(skb->cb), , sizeof(dev));
skb_push(skb, priv->rtllib->tx_headroom);
ret = _rtl92e_tx(dev, skb);
-   if (ret != 0)
-   kfree_skb(skb);
 
if (queue_index != MGNT_QUEUE) {
priv->rtllib->stats.tx_bytes += (skb->len -
 priv->rtllib->tx_headroom);
priv->rtllib->stats.tx_packets++;
}
+
+   if (ret != 0)
+   kfree_skb(skb);
 }
 
 static int _rtl92e_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
-- 
2.7.4

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